c : Ai bapa bere sHsereues Lees hole ence ene re a et iad antes erene me nae Senet cea bed a Biers s Lani a eee Diner aay eee ALBERT R. MANN LIBRARY “NEW YorkK STATE COLLEGES OF AGRICULTURE AND HoME ECONOMICS AT CORNELL UNIVERSITY Cornell University Library QK 569.D54B79D WT 3 1924 000 413 660 vic! i mann THE DIATOMACEAE OF PHILADELPHIA AND VICINITY by Charles S. Boyer u [Pte university MIcRoFILMS © Ann Arbor, Michigan THE, DIATOMACE& OF | PHILADELPHIA AND VICINITY BY CHARLES S. BOYER, A.M., F.R.M:S. ILLUSTRATED WITH SEVEN HUN- DRED DRAWINGS BY THE AUTHOR PRESS OF J. B. LIPPINCOTT COMPANY EAST WASHINGTON SQUARE PHILADELPHIA 1916 Missing Page PREFACE The present contribution to the local flora is intended as an infroduction to more extended research. The study is of advantage in relation to the life history of aquatic animals, the deter- mination of ocean currents, as proved by polar discoveries, the invest'gation of geological strata where other fossil forms are absent, and the analysis of water supply; and, when we consider the universal distribution of diatomacee in the earth, the water and even in the air and the enormous deposits formed in past ages and still forming, we are able to realize the importance of a knowledge of these complicated forms and their function of purification. The absence of descriptive works of reference in available form in this country, the polyglot confusion of authorities abroad and the amount of time, patience and skill re- quired in obtaining, preparing and examining specimens, render the study one of difficulty. The bibliography is omitted, as it is understood by those who possess the works of reference, and but few synonyms are given, having but little, except historical, value, espe- cially when it is considered that modern investigators have no access to many of the earlier collections, when any of these exist. So far as the marine forms are concerned, it is probable that nearly all occurring north of Florida are here included, and the fresh-water species described represent a large proportion of those found east of the Alleghanies. All of the figures are drawn to the same scale, a magnification of eight hundred diameters, from specimens in my possession, nearly all of which were found in or near Philadelphia. If the work is of any value in inducing further investigation, I hope, in the words of Julien Deby, that “those who follow my advice will find in the study of these wonderful little organisms as much pleasure as I myself have found.” Tue AUTHOR. COPYRIGHT, 1916, BY CHARLES S, BOYER \ INTRODUCTION The Delaware River rises in the Western Catskill Mountains, flows southward for about three hundred and seventy-five miles, and expands into Delaware Bay about sixty miles from thesea. Its origin is among the Devonian and Carboniferous rocks, and in its course it passes through Silurian, Triassic and Cretaceous formations, finally reaching the Cambrian and Laurentian beds. It also drains regions of the glacial drift and beds which overlie over- turned Miocene strata, and are sometimes mixed with them. From the mountains, nearly four thousand feet high, to the Bay, where the depth of water is not greater than seventy- five feet, the diatomaceous flora, from Alpine cascades to the salt marshes of New Jersey, contains a larger number of species than any other equal portion of the American coast. The city of Philadelphia, about one hundred miles from the sea, lies at the junction of the Schuylkill with the Delaware, and much of the land near the rivers, especially south- ward, is flat and low, composed of recent alluvial deposits. In the central districts the ground is high, the deep sub-soil being mostly a dry gravel resting upon gneiss and schist, although it is in part composed of a bluish clay which was probably laid down in the bed of the ancient river before the last period of the glacial drift. The blue clay was not all de- posited at the same time, as in the lower strata many marine forms are found which do not occur in the upper layers. This is notably the case in a deposit obtained at Spreckel’s Sugar Refinery and also at the east end of Walnut Street Bridge, where a layer of blue clay occurs which is overlain by glacial drift. In other parts of the city mixtures of blue clay with more recent deposits are found, including fresh-water forms from numerous creeks and rivulets which traversed what is now the city proper, and especially from the vicinity of Fourth and Market Streets, where there existed as late as the year 1700 a large pond known as the “ Duck Pond” which was subject to tidal overflow from its outlet, Dock Creek. The river water at Philadelphia is not noticeably brackish, although the tide extends thirty miles above the city and, before the building of Fairmount Dam, to the Falls of the Schuylkill. At certain times, when the river is low, the influx of tide water is sufficient to produce an abundance of brack- ish water diatoms at Greenwich Point. The entire absence, however, at present, of many of the marine forms obtained in dredgings in the Delaware opposite the city, as at Smith’s Isiand, now removed, and in certain well borings at Pavonia, Pensauken, Gloucester and other places in New Jersey, where the depth reached the old blue clay, indicates conditions quite different from those now prevalent. In the Bay itself comparatively few living species are found, at least in any abundance. In tke study of local forms which follows, the district included’ may be considered as circumscribed by the circumference of a circle having a radius of one hundred miles from Philadelphia, containing the States of New Jersey and Delaware, the southeastern part of 5 6 INTRODUCTION Pennsylvania, a portion of Maryland on the south and extending eastward to New York Bay and Long Island Sound as far as New Rochelle. The greater number of fresh-water species described have been obtained from near the city along the Darby, Crum, Ridley and Brandywine Creeks and from various places in New Jersey, including the Pine Barren region of the southern part of the State. Numerous collections have been made in the Schuy]kill and the various reservoirs and along the Wissa- hickon, ‘‘where an Alpine gorge in miniature of singular loveliness is to be found within the limits of a city.”” The fossil deposits are from well borings near Camden, N. J., and from excavations in various parts of the city. There appears to be no relation between the Miocene beds of the eastern coast and the deposits here described, all of which have been formed later than the glacial period or in an interval between two such periods. Apparently no diatoms grew during the glacial era, at least in sufficient abundance to leave any perceptible traces of their existence. An examination of glacial ‘‘fiour” and clays from the Catskills shows an entire absence of these forms, and I have never found them in the milky flow from the glaciers of the Alps nor in the constantly muddy streams in certain of our Western States. The opacity of the water produces the same result as the absence of light in the deep lakes of New England, where diatoms are found only on the stalks or roots of water-plants near the shore, while in shallow ponds, such as the small lake near the summit of Mt. Lafayette, the growth is abundant. Certain species will grow wherever there are moisture, light and heat, but the greater number require the presence, in small amounts, of substances pro- duced by the decay of animal and vegetable life. An abundance of diatoms in fresh water is usually an indication of its potability, while their entire absence in shallow water may be due to an excess of bacteria. The specimens from which the drawings are made have been collected by the author for many years; in addition to possessing an almost complete library on the subject, he has had the advantage of examining material obtained by the late Mr. Lewis Woolman and numerous slides furnished by a number of friends, including Mr. John A. Shulze, Mr. Frank J. Keeley and Mr. T. Chalkley Palmer, to whom I here take pleasure in expressing my thanks. The difficulties of the study are well stated by Agardh in the following extract from the preface to his Systema Algarum: ‘Because, indeed, in this respect, no one will wonder whether in the distinction of spe- cies and reference to synonyms we have, perchance, committed many errors. They have occurred and are bound to occur, partly from the fact that one is not permitted to see the original specimens of all authors; partly, because sometimes even the original specimens of these plants are erroneous; partly, because the figures and descriptions of authors are often lacking and imperfect. . . . . “There is added the difficulty of the study itself of these plants, their submerged habitat, the minuteness of their structure, the rarity of their fruit, the change in the dried INTRODUCTION 4 plant, the impossibility of culture, the fallacies of microscopical vision and the chaotic condition of Algology itself to-day.” The words of Agardh, written in 1824, are almost as true to-day. The lack of authentic specimens, which we hope will be remedied in time by the collections of the Smithsonian Institute, numerous incorrectly labelled slides in amateur collections,’ the imperfections of figures copied and recopied, without regard to relative size or correct references, and the confusion in the attempts to harmonize different descriptions, deter the student at the outset. The remaining difficulties mentioned by Agardh add, how- ever, to the remarkable interest these forms have always had, since no increase in optical perfection of the microscope serves to lessen the mystery of their structure and mode of growth. CLASSIFICATION The few species of diatoms first discovered were included by Lyngbye, Dillwyn, and others in the genus Conferva. In 1824, the species, increased to forty-eight, were separated by Agardh into eight genera distinguished partly by their mode of growth. But little change was made until Heiberg, in 1863, advocated the division into symmetrical and asymmetri- cal forms. Without entering upon a general review of the later classifications, including Pfitzer’s and Petit’s divisions according to the number and location of the chromatophores, or the arrangement of Prof. H. L. Smith, because of the presence or absence of a raphe, or that of Mereschkowsky into motile and immotile forms, the modification of all of these methods by Schuett is here adopted, varied in accordance with certain monographs which appear to offer advantage. It is customary, especially among writers who are familiar with other classes of plants, to decry any classification of diatoms according to the markings of their siliceous envelopes. As, however, one of the chief distinctions of the class is the possession of a more or less siliceous and indestructible frusiule, and as the cell and its contents are never seen except within the valves, their variety forms the only available method of identification. The cell contents, owing to the difficulty of observing their living condition, their continued change, their lack of distinct variation and their entire absence in fossil forms, render their con- sideration as a complete method of classification an impossibility. If, however, the cell contents can be brought into relation with the markings of their siliceous envelope, it will be a consummation for which the future student of these complicated forms ought to be grateful. That this result is one to be expected may be inferred from the fact that the arrangement of protoplasmic masses in the interior of the cell is coincident in some cases with markings on the valve, and the character of the endochrome is assuming a certain value in accentuating the difference between such forms as Pleurosigma and Gyrosigma, or in the resemblance between Hantzschia and Nitzschia, or between Surirella and Campy- lodiscus. Mereschkowsky, however, states that it is necessary to be careful in ‘‘establish- ing the relationship between diatoms based on the resemblance of their chromatophores,” 8 INTRODUCTION and further observes that in Hantzschia amphiorys, Scoliotropis latestriata and Achnanthes brevipes, three widely separated forms, the chromatophores are essentially the same. In one of the earliest classifications of diatoms, the individual cell received less con- sideration than the nature of the filament or thallus in which many species occur in the first stages of their growth. Those, however, which exist in colonies at first are, sooner or later, broken up into separate frustules, either before or at the time of their maturity or previous to conjugation, while very many species are never seen except in a free state. The union of frustules, therefore, is of secondary importance and the group must be considered as filamentous or unicellular alge. Their relation to other alge is not well determined. Among the Desmidiacee, a family of the order Conjugales, of the class Chlorophycee, the cells are in many forms divided by a constriction into symmetrical halves. The Conjugales are starch forining, with walls of cellulose. In the Diatomacez the starch is replaced by oil globules, while the walls of ceilulose are more or less filled with a deposit of silica. The Conjugates, however, repreduce by zygospores and usually contain pyrenoids, as may be seen in the parietal chromatophores of Spirogyra. In the class Heterokonte we have the reserve materia! in the form of oil, instead of starch, but there are no pyrenoids. To this class belongs the order Confervacee, in which the cells are unicellular or filamentous, and to which all of the Diatomacee were referred. While, therefore, Diatomacez have a close affinity to the Desmidiacex and to the Confervacez, the determination of their origin, one from another, or from a common ancestral type, appears to be a matter of conjecture. MORPHOLOGY AND DEVELOPMENT THE CELL The cell membrane is composed of two usually equal parts, each of which consists of a valve and a girdle or zone formed of cellulose modified by silica deposited in an insoluble state from a very dilute aqueous solution. The valves are more siliceous and robust than the girdle. Both are in most species easily separable, or at least the bands of the girdle which may be more or less closely fastened to the valves have a motion over each other permitting the cell to en- large at pleasure. The longitudinal diameter of the cell, or the distance between the centres of the two valves, will vary according to the convexity of the valve and the age of the frustule which may be often determined by the width or number of the girdlebands. These, owing to their diversity of form and arrangement, will be further described under the generic diagnoses. The siliceous cell-wall is covered on the outside by a layer of protoplasm called the coleo- derm. Thislayer may be quite thin and evident only when treated with fuchsin or Bismarck brown, or it may be of considerable thickness. The cell contains the cytoplasma, protoplasm, cell-sap, endochrome, pyrenoids, oil globules and nucleus, together with certain other less understood bodies. The Cytoplasma is a thin skin of colorless plasma covering the entire inner surface of the cell. It is invisible in the living cell but is evident in plasmolysis. In long forms it is thickened at the ends and is condensed at the plasma bridge which frequently con- nects the two valves and divides the cell into two parts, each containing more or less pro- toplasm surrounding the vacuole in which are found the cell-sap and certain granules. In some forms, as Meloseira, the cytoplasma includes the entire mass of protoplasm. The Endochrome is seen in the form of one or more bands or plates, of a yellowish or brownish color, on the inner side of the valves or connective zone, or in granules or irregular masses, more or less numerous, on the inner walls, or sometimes grouped near the centre. It consists of a mixture of chlorophyll and diatomine which differ in their relative solubility in alcohol and in their spectroscopic analyses. The color varies from green to a chocolate brown in proportion to the amount of diatomine. So far as the func- tion of the endochrome is concerned it does not appear to differ from that of ordinary chlorophyll, absorbing, under the influence of light, the carbon, and disengaging the oxygen of the carbonic anhydride ir the water. Diatoms do not live in absolutely pure or non- acrated water. Tie individual plates or granules of the endochrome are called chromato- phores. Their number and significance will be referred to in the description of genera. Tue Pyrenoiws.—In the chromatophores of many species are found colorless, homo- geneous bodies, strongly refractive, of various shapes, usually lenticular or fusiform, which are known as Pyrenoids (Schmitz). They are scarcely evident in the living cell, but are distinguished by the action of hematoxylin and other reagents. Flat forms occur in Surirella and Pleurosigma, lens forms in Pinnularia, Stauroneis, Synedra, Fragilaria and Nitzschia, while a spherical form is found in Cymbella cuspidata. The pyrencids are always imbedded in the chromatophore. Their growth is by division. Schmitz con- siders them a part of the living chromatophore, and their substance as working material which in excess has become resolved into the nature of a crystal which its form sometimes re- sembles. Comparisons are made between them and crystalloids found in certain monocoty- ledons. The pyrenoid is evidently concerned in the formation of the chromatophore, or in its division. Much of the conjecture, however, is due to the behavior of pyrenoids in other plants. 9 10 THE DIATOMACL.X OF PHILADELPHIA AND VICINITY O1_ GLosuLes.—It has been established by Pfitzer that starch and sugar, as assimila- tion products, are replaced by oil in the cells of diatoms (‘‘da bekannlich Staerke und Zucker bei den Bacillariaceen nicht nachzuweisen sind”). The oil drops are more or less numerous, of various sizes, and are found in the cytoplasma, the cell-sap, and sometimes the chroma- tophores. Mereschkowsky describes certain globules as elxoplasts, which he divides into four kinds according to their number and position. Whether all of these are oil globules is a question not yet determined. Other bodies, known as ‘‘ Buetschli granules,” or volutin, and described as ‘‘little blisters filled with a tolerably robust refractive substance,’’ are considered by Lauterborn to be a nitrogen reserve store. They are found in the cytoplasma, or in the cell-sap, and can be fixed in picric acid and stained in methylene blue. Note.—For a discussion of the morphology of diatoms and a valuable résumé of the investigations of Buetschli, Karsten, Lauterborn, Mereschkowsky, Mueller, Pfitzer, Schuett, and others, the student is referred to ‘‘Der Bau der Diatomzelle,”’ by Dr. Otto Heinzerling, in ‘‘Bibliotheca Botanica,” 1908. CELL Division The growth of diatoms follows the usual method of cell division as described by Sachs (Text Book of Botany, 2nd ed., p. 16): ‘‘The nucleus of a cell which is about to divide becomes broader, assuming the form of a biconcave lens, and its nucleolus breaks up into irregular granules which together with its other granular contents begin to form a nuclear disc in the equatorial plane. A delicate striatioa is now apparent in what is becoming the long axis of the nucleus, at right angles to the nuclear disc, and the characteristic nuclear spindle is gradually produced. The nuclear disc splits into two halves lying side by side, each of which travels to the corresponding pole of the nucleus; thus two nuclei are consti- tuted which are connected by fibrille.”’ The cell-wall and the chromatophore bards divide, each nucleus passes to the centre, and two new cells are formed. In the meantime, to permit of this division, the two sili- ceous valves separate, the girdle bands slipping over each other, and opposite the larger or enclosing valve a new valve is formed, the girdle band of which is seen later within the girdle cf the mother valve. Opposite the smaller vatve of the original cell and adjoining the new valve, another valve is formed which also produces a girdle within the girdle of the smaller valve. Asa result of division we have, therefore, the valves of the original, or mother cell, the two new valves and four girdle bands. (Pl. 40, Figs. 18 and 19.) In the process of division, the continual formation of new valves, enclosed in the older girdle bands, will naturally cause a reduction in the size of the frustule. While this reduc- tion, owing to the elasticity of the girdle, does not always occur, I believe, yet, in most cases, the diameter is so reduced that a rejuvenescence of growth is required. This is caused by the production of auxospores which may appear without conjugation. In this process, the beginning of which, in certain species, may be noticed by the increase in the size of the girdle as in reduplication, the two valves separate and within is formed a moreor less spherical mass about twice the size of the original frustule and which forms on its circumference two large and often shapeless valves. These valves form others which assume the appearance of the original valves, but larger, and proceed to grow in the usual way. The reduction in size of the frustule seldom proceeds further than about half the size of the type form, so that, as a general rule, it may be stated that diatoms are not often smaller than half the larger size. REPRODUCTION The process of reproduction has been observed in many cases, but the conclusions reached are somewhat at variance with each other. The auxospore formation is simply a THE DIATOMACE.E OF PHILADELPHIA AND VICINITY u method of rejuvenescence. When, however, the auxospores are thrown off from filamentous diatoms, it is probable that two may conjugate, their contents dividing each into two daugh- ter cells which unite into two zygospores. The usual method is the union of two frustuies, which, throwing off the old valves, coalesce into a single mass of protoplasm which produces an auxospore, sometimes called a sporangial frustule. It is stated that in some cases two frustules coalesce and produce two auxospores. The existence of spores in diatoms is a much-disputed point. While they have never been seen, the inference that they exist is very great, as otherwise it becomes difficult to understand the sudden growth cf species in localities and under conditions that seem to preclude the actual presence of the living frustule. It is a matter of common observation that, in examining collections of living forms, minute frustules or brownish globules appear to resemble larger diatoms. In gatherings of Gomphonema, when many specimens are sessile on the same object, numerous intermediate sizes, varying from minute globules to the type, are seen, yet not positively demonstrable as the same. Conjugation, the formation of auxospores, and the actual process of cell division are seldom seen, as they occur during the night or at least in darkness. It is advisable in order to observe reduplication to obtain the material about midnight and place it in very dilute alcohol. In filamentous forms, however, the cell division is easily observed at any time in its various stages. By immersing in picric acid (saturated solution), transferring to very dilute alcohol which is gradually increased in strength, and then passing through oil of cloves and finally to the mounting medium, excellent preparations can be made. By stain- ing with gold chloride alone the nucleus is made apparent without further treatment. Evoiction or Forms It may be assumed that diatoms originated in the sea; to deny this requires evidence of the existence of fresh-water species previous to the Miocene period which is entirely marine. In those subject to fluctuations of the waves, as pelagic diatoms, their existence appears to be contingent upon the methods by which the separate frustules can cohere. Various devices, including hooks, spiral bundles, horns and processes exuding threads of plasma, exist for holding together the frustules. When marine forms are found in quiet waters come of these devices, being no longer of any value, cease to grow, although free swimming diatoms are rare. They either occur in long chains or are stipitate or sessile. If it is further assumed that the fresh-water diatoms are found in greater abundance in later periods, the action of running streams makes necessary the provision of seme means by which the species may continue to colonize. This may be recognized in the occurrence of linear forms chiefly in streams. / Circular forms, such as Cyclotella which have no raphe, are found in quiet waters, such as pools or ditches, and never exist living in running streams. Those forms only would be able to live in water having a more or less swift current under one of three conditions: they must, as in Gomphonema, be adherent to surrounding objects by a stipe; or be enclosed in a gelatinous tube, as in Homeeocladia; or have an independent motion powerful enough to overcome the influence of the current. It is true that many forms with araphe have no apparent motion. In the case of Mastogloia provision is made in a gelat- inous cushion in which the frustules are preserved. In Cocconeis, with a true raphe in one valve only, in Epithemia, with a partial raphe, or in certain Eunotie with a trace of one, we find species evidently degenerate and parasitic. The long Synedre, having only a median line, live in running streams, since they are attached at one end to other alge. Forms with a true raphe appear to be more highly developed, since they are able to seek locations favor- able to growth. Given, therefore, the structure of the valve, the habitat may be inferred. 12 THE DIATOMACE OF PHILADELPHIA AND VICINITY Tre Motion or D1atoms The erratic backward and forward movement of certain diatoms, especially those of the Naviculaid group, or the slow, rolling motion of Surirella, has been discussed in so many ways without definite conclusions that a brief statement will be sufficient. Osmosis, the amceboid movement of the coleoderm, the protrusion of protoplasm or protoplasmic threads through the raphe, the existence of actual organs of locomotion or cilia, and the lack of synchronism in the chemical action occurring at the ends of the cell which is sometimes divided by the plasma bridge, have been offered in explanation. The chief objection to the theory of cyclosis appears to be that the resultant motion is so greatly in excess of the rota- tion of pretoplasm in the cell. More or less motion is observed in various kinds of free cells, but the movement of diatoms is not evident in those without either a raphe or a keel upon which and apparently by which the phenomena are produced. Mr. T. Chalkley Palmer, in various articles in the Proceedings of the Delaware County Institute of Science, especially in Vols. 1 and 3, gives the results of exhaustive experiments. “Nothing, it would seem,” he says, ‘‘could be more conclusive as to the essential sameness of the nature of motion in monads and diatoms, than the fact that both monads and diatoms require oxygen in order to perform motion, that they come to rest when oxygen becomes scarce, and that they resume their motion when oxygen is again supplied.” He also thinks ‘‘that the living substance of the cell, more or less deeply overlaid with coleoderm substance of varying consistency, and itself assuming that degree of fluidity which best meets the requirements of the situation, permeates the raphes, circulates in the keels, or in some cases protrudes quite beyond the silica, and functions as the actual pro- pulsive agent.” Tur Function or Dratoms Of all forms of vegetation, the Diatomace2 are, perhaps, the most ubiquitous. Where- ever a sufficient amount of moisture, heat and light are found, they grow. It was during the Miocene period that they first appeared, and, as marine forms, reached their greatest development, both as to size and beauty of marking, while their prevalence throughout the world in enormous quantities has been often mentioned. The Miocene beds of Richmond and Maryland continued over the Cretaceous formations of New Jersey have outcropped in certain localities within our district, but are not considered in this discussion. The function of diatoms is not essentially different from that of other alge in provid- ing food for aquatic animals, such as Salpz and oysters, but it is. however, in other respects that they are not only important but necessary factors in the preservation of life. “Full nature swarms with life; one wondrous mass Of animals, or atoms organized, Waiting the vital breath, when parent heaven Shall bid his spirit blow. The hoary fen, In putrid streams, emits the living cloud Of pestilence. Thro’ subterranean cells Where searching sunbeams scarce can find a way, Earth animated heaves.” I am not certain if Thomson fully understood the matter, but he has remarkably described the facts. When “‘the vital breath” of returning spring animates the earth, the “subterranean cells” of diatoms, the ‘‘atoms organized,” through the liberation of vast quantities of oxygen, immediately begin the purification of the ‘‘putrid streams.’’? Were these streams not so purified, the accumulation of animal and vegetable débris would event- ually cause an enormeus bacterial growth fatal to animal life. DIATOMACEA Unicellular or filamentous. Cells either free, sessile, united in filaments, immersed in a gelatinous envelope or in fronds composed of branching tubes; microscopic, enclosed in a more or less siliceous envelope (frustule), composed of two parts (valves), usually connected by an intervening band (zone or girdle). Cell contents include yellowish or brownish chloro- phyll-like bodies which occur in one or several bands (placcochromatic), or as variously dis- tributed granular masses (coccochromatic) lining the-inner walls. Growth by ordinary cell division or by auxospores; sexual multiplication by the formation of sporangia. Valves of two kinds: (a) Those in which the markings or parts are more or less concentric (Centric) ; (b) Those (Pennatz) in which the parts are mure or less symmetrically divided by a line (pseudoraphe) or by a cleft (raphe). CENTRIC Valves without a dividing line or cleft; markings more or less radiate; transverse section of frustule circular, polygonal, or elliptical, sometimes irregular. Divided into four groups: 1. Discoidee.—Frustules ea discoid; valves without horns or elevations (sometimes ~ with processes). 2. Solenoideew.—Frustules sith numerous girdle bands. 3. Biddulphioidew.—Frustules box-like, 7. e., with the longitudinal axis greater than in the Discoidex. Valves with two or more een elevations or horns. 4. Rutilarioidee.—Valves as if naviculoid, but with irregular or radial structure. Groups 2 and 4 are not included in our description. No. 2 contains plankton genera only, while No. 4 consists of genera not yet found in this locality. DISCOIDE.E 1. Coscinodiscee.—Valve not divided by rays or costz into sectors; puncta sometimes radiate; ocelli or processes absent. 2. Actinodiscee.—Valve with radial strive divided into sectors; ocelli and processes absent. 3. Eupodiscee.—Valve disc-shaped with mammiform processes or one or more ocelli. 1. COSCINODISCEE (a) Afeloseirine.—Frustules short, in chains. (b) Coscinodiscine.—Frustules dise form, usually single, rarely in short chains. (a) MELOSEIRINZ 1. Meloseira.—Valve punctate, with a constriction or furrow between edge of valve and girdle. : . Gaillonella.—Valve punctate, with a circular collar or crest near edge of valve. . Lysigonium.—Valve punctate, neither keeled nor constricted. . Hyalodiscus.--Valve punctate in the centre; border with decussating radial lines. Stephanopyzis.—Border of valve with a crown of thorns; valve areolate. Pyzxidicula.—Valve areolate, with a border of spines. Doni wr 13 14 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY ME toseErra Aa. (1824), em. De Tont (1892) (melos, a limb or member, and seira, a chain) Frustules globose, ellipsoidal or cylindrical, concatenate, closely joined together. Valve either simply punctate or punctate and areolate. A constriction of the cell-wall, forming a furrow between the edge of the valve and the girdle, is more or less evident. . The genus Meloseira constituted by Agardh has been variously modified by Kuetzing, Thwaites, Wm. Smith, Van Heurck, De Toni, and others. In Systema Algarum Agardh included certain species of Conferva, of Lyngbye, Dillwyn and others, and limited his genus to frustules more or less globose (fila articulata ad genicula constricta), although in his Con- spectus Criticus (p. 64), he modifies the description (fila teretia articulata, articulis diametro zequalibus vel longioribus) to include M. varians. As, however, Lysigonium Link, Gaillon- ella Bory, and other genera enlarged by Ehrenberg and Kuetzing, came to be included under Meloseira, Thwaites suggested the division of the genus into two: Orthosira, in which the frustules are not convex at the ends and Aulacosira in which no central line is apparent but with two distinct sulci. Wm. Smith adopts the genus Orthosira but rejects Aulacosira, including all forms under the former genus and Meloseira, suggesting that differences “‘exist in the formation of the sporangia” of the two genera. M. varians and M. crenulata appear to form auxospores or sporangial frustules in different ways, as will be noticed Lereafter. As, however, the present state of our knowledge is so limited and as much confusion would result in further changing the nomenclature, I shall adopt, for the most part, the divi- sion made by De Toni, separating Gaillonella and Lysigonium and employing the name Melo- seira as emendated in Sylloge Algarum, although, as stated, it omits the species of Agardh. That a further division may be necessary is indicated by the differences existing between the Orthosira forms and the others. ANALYSIS OF SPECIES Frustules cylindrical and lengthened: Valves with two distinct furrows; granules small ................. distans Valves with coarse granules ........ siuie =o PUN BeRe re eNenMHecs granulata Valves denticulate on the margin ............. 2c. cece eee eee crenulata Valves denticulate and constricted ............... 0.0 c cee ee cece Toeseana Valves with row of large puncta on the girdle side............... undulata Frustules cylindrical and compressed: Valves punctate and areolate ........... 0... c cee ceca eee sulcata The chromatophores consist of circular and compressed or irregular flat granules which lie along the wall of the cell. MELOSEIRA DISTANS (EHR.) KUETZ. Frustules cylindrical, slender, with two furrows, one on each side of the suture; valve in zone view with fine puncta in longitudinal rows; puncta in valve view scattered. L. 7-104. Meloscira nivalis Wm. Sm. Coscinodiscus minor Wm. Sm. Fresh water. Fossil in New England deposits. Pl. 1, Figs. 8 and 9. Note.—In all species of Meloseira, as well as Gaillonella and Lysigonium, the frustules are so closely coherent that when the filaments are broken entire frustules are less frequently found than a union of two valves of contiguous frustules. ; THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 15 MELOSEIRA GRANULATA (EHR.) RALFS Frustules cylindrical, robust, 5-18 » in diam., with large granules in longitudinal, some- times spiral, lines, variable in size and arrangement in the same filament. Valve in valve view with scattered puncta. Variable in relative width and length, passing to M. crenulata. Gaillonella granulata Er. Orthosira punctata Wm. Sm. Fresh water. Fossil at Coldspring, L. I. Pl. 1, Fig. 10. MELOSEIRA CRENULATA (EHR.) KUETZ. Frustules cylindrical, with furrows on each side of the suture, 10-20 » in diam.; puncta in longitudinal rows. Margins of valves denticulate at the junction of the frustules; valves with puncta scattered at the centre, radiate at the circumference. Common in fresh water; quite variable in size. Gaillonella crenulata Ehr. Orthosira orichalcea Wm. Sm. in part; not Conferva orichalcea Mertens or Gaillonella aurichalcea Ehr. and Bailey. Pl. 1, Figs. 1 and 2. MELOSEIRA ROESEANA RAB. Frustules cylindrical, constricted toward each end, with coarse, longitudinal striz; valve convex, striz punctate, radiating, with several large granules at the centre. Connec- tive zone with longitudinal rows of fine puncta. Diam. 12-45 p. Orthosira spinosa Grev. Fresh water. Media, Pa. (Palmer ); not common. Pl. 1, Figs. 5 and 6. MELOSEIRA ROESEANA VAR. EPIDENDRON (EHR.) GRUN. Frustules denticulate at the margin; valve with coarse granules at the centre from which radiate lines of fine puncta. Wet rocks of the Wissahickon. Pl. 1, Figs. 3 and 4. MELOSEIRA UNDULATA (EHR.) KUETZ. Frustules single or in twos, usually broader than !ong, constricted near the margin. Valve with six to twelve internal projections forming with the outline of the constriction of the valve a polygona! figure within the circumference. Surface of the valve with radiat- ing lines of puncta disappearing toward the centre, at which are numerous coarse puncta. Meloseira gowenii A. Schmidt. Blue clay of Philadelphia, especially common at Twelfth and Market Sts. Pi. 1, Figs. 15, 16, 17. MELOSEIRA SULCATA KUETZ. Frustules quite robust, with diam. several times the length, deeply furrowed at the margin, areolate and punctate. Valve with radiating stria disappearing toward the centre, and with a double row of cells near the margin, the outer one having the appearance of a crown of teeth. Gaillonella sulcata Ehr. Paralia sulcata (Ebr.) Cleve. Paralia marina Heib. 2 16 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY Marine and brackish. Common in all parts of the world, and fossil in the Miocene. The Philadelphia form is the var. genuina Grun. Pl. 1, Figs. 11 and 12. In a gathering from Media of Meloseira crenulata (Palmer leg.), occasional filaments are noticed with much longer and narrower frustules which become enlarged in the middle and are seen to contain inner frustules in the process of still further division, as shown in Fig. 2, Pl. 38. Meloscira dickei Thwaites shows internal box-like cells placed one within the other, which were supposed by Thwaites to be a method of reproduction. Wm. Smith doubts this, but is unable to offer any explanation. In the present form the mode of reduplication is that usually found in filamentous forms, but in this case the presence of perfect frustules enclosing others in the process of stil! further division has been heretofore unfamiliar to me. The swelling in the middle appears to indicate that not all filamentous diatoms are reduced in size by subdivision. In outline the valve is like that of a ‘‘truncated cone,’ as described by Petit in referring to Gaillonella granulata var. bambusina Petit (Diat. Nouv. et Rares, Jour. de Micrographie, 1890). GAILLONELLA Bory DE St. VINCENT (1823) (named after Gaillon, a botanist of Dieppe) Trustules ellipsoidal, united in long filaments, usually found in pairs; each valve is furnished with a circular collar or crest extending at right angles to the convex edge. Valve hyaline at the centre from near which radiate lines of fine puncta, 18-20 in 10 p. Note.—The original names of both Meloseira and Gaillonella are retained, as there is no good reason for contracting the Greek diphthong in the first, and the second is the correct spelling. GAILLONELLA NUMMULOIDES (DILLW.) BORY Frustules as in the generic diagnosis. Diam. 30 yu. Conferva nummuloides Dillwyn (Brit. Conferve, p. 45, Sup. Pl. B). Meloseira nummuloides Ag. Heiberg and O’Meara assign this species to Lysigontum moniliforme (Muell.) Link, which is not keeled. While Dillwyn’s and Lyngbye’s figures do not show the keel, it is probable from their descriptions that the angular outline produced by the keel was noticed. Marine or brackish. Coast of New Jersey; Hudson River (Bail.). Pl. 1, Figs. 13 and 14. Gaillonella moniliformis of Bailey is this form, as he describes it as having ‘‘two minute projections of the delicate transverse ridges seen near the ends of the two globules belong- ing toa joint.” (Amer. Jour. Science, 1842, p. 89, Pl. 2, Fig. 3.) Lystcontum Linx (1820) (luo, to loose, and gonu, a joint) Frustules globose, concatenate; valve simply punctate. LYSIGONIUM MONILIFORME (MUELL.) LINK Frustules usually in twos, not keeled; valve with puncta in longitudinal lines, the puncta of the enveloping zone larger and in transverse rows. L. 25-40 u (De Toni). Conferva moniliformis Mueller (1783). THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 17 Conferra nummuloides Eng. Bot. pl., 2287, not Dillwyn. Meloseira borrert Grev. Lysigonium nummuloides (Lyngb., Kuetz.) O’Meara=Gaillonella nummuloides (Dillw.) Bory. See O’Meara, p. 248. Marine and brackish. Long Island Sound and coast of New Jersey. Pl. 1, Fig. 7. LYSIGONIUM VARIANS (AG.) DE TONI Frustules cylindrical, in long filaments, slightly constricted on each side of the suture; puncta in oblique rows in zone view. Valves 15-35 u in diam. (De Toni), sub-plane, with fine puncta in lines radiating from the centre. Under medium magnification the frustules appear smooth. Very variable in size. Meloseira varians Ag. Fresh water. Common in ditches and springs. Pl. 1, Figs. 18 and 19. Hyavopisctus Eur. (1845) (hyalos, transparent, and discus, a disc) Frustuics spheroidal; valve with a flattened, irregularly punctate umbilicus from which proceed radiating or decussating lines of fine puncta. ANALYSIS OF SPECIES Valves. divided Into S€CtOrsSie.c.ccc.ecedernewi nese eeeaeee beeeess stelliger Valves not divided but interrupted by short dark lines at intervals.... radiatus Valves with “éry fine punta. coc. 000902 anaee suena weresae ee ies scoticus HYALODISCUS STELLIGER BAIL. Valve with puncta in oblique decussating rows which, by reason of the difference in obliquity, form numerous sectors. Umbilicus irregular, with scattered, coarse puncta. Margin wide, striated. Podosira maculata Wm. Sm. Blue clay. Not common. Pl. 1, Fig. 22. HYALODISCUS RADIATUS VAR. ARCTICA GRUN. Valve with radiating puncta from a rather small umbilicus, the rays interspersed with short, dark lines, having the appearance of spines, at irregular intervals. Margin broad, striated. Pyzxidicula radiata O’ Meara. The Philadelphia form corresponds exactly to Grunow’s variety which has closer puncta than the type form. Blue ciay. Rather rare. Pl, 1, Fig, Zi. 18 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY HYALODISCUS SCO'ICUS (KUETZ.) GRUN. Valve small, with puncta about 24 in 10 yw, appearing hyaline. De Toni remarks that it resembles a small form of H. subtilis which occurs north and south of our limits and is yet likely to be recorded. Cyclotella scotica Kuetz. Podosira hormoides Wm. Sm. Blue clay. Not rare. Pl. 1, Fig. 20. Endochrome in the form of four flaps or patches bound together about a common pyrenoid. In H. subtilis numerous rod-shaped chromatophores lie in a row and are not— bound in the centre (Mereschkowsky). STEPHANOPYXIS ExR. (1844) em. Grun. (1884) (stephanos, a crown, and pyxis, a kind of vase or box) Frustules ellipsoidal, concatenate; valves tumid, of unequal convexity, coarsely areo- late, the cells in rows parallel to the longitudinal axis, not radiate, with stray spines or teeth placed concentrically more or less near the margin. According to Karsten the chromatophores are round or angular discs which lie near the connective zone. STEPHANOPYXIS TURRIS (GREV.) RALFS Valve cylindrical, with a crown of stout spines less than the diameter of the valve near the margin. Cells hexagonal, about 2 in 10 #, sometimes punctate. The valve hav- ing the greater convexity has the larger spines, though usually less of them. Creswellia turris Grev. (Gregory, Diat. of the Clyde, T. R.S. E., vol. 21, part 4, p. 66.) Stephanopyxis appendiculata Ehr.? Creswellia is incorrectly based, as stated by Ralfs, on the concatenation of the valves which was not noticed by Ehrenberg in the fossil forms. It had been suggested by Kuetz- ing in Systema Algarum (p. 126). Blue clay. Port Penn and Smith’s Island. Pl. 2, Figs. 1 and 2. STEPHANOPYXIS CORONA (EHR.) GRUN. Valve larger than in turris, sub-globose, coarsely areolate cells, 4-5 in 10 #. One valve furnished with a crown of teeth shaped like the letter T and united at the top into a ring above the margin of the valve; the other valve with long spines more or less concentrically arranged. Blue clay. Not common. Fossil in the Nottingham deposit. Pl. 2, Fig. 3. Nore.—The diatomaceous deposit, so often called ‘‘ Bermuda”’ or ‘‘ Bermuda tripoli,” especially by foreign writers, is in reality the Miocene stratum extending for miles along the Patuxent River near the village of Nottingham, Md. The author is perfectly familiar with the location, having made large collections there. The mistake in the name is due to the fact that Pref. Bailey received material from Mr. Tuomey marked “Bermuda Hun- dred,” which is located near Petersburg, Va. Attempts have been made to find material there and while there is an earth containing Miocene diatoms at Petersburg, it does not exactly correspond to the material sent to Ehrenberg by Bailey, who was in doubt as to the locality. The Bermuda Islands are of corel formation and have no deposits of diatomaceous earth. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 19 Pyxivictxa Eur. (1833) (dim. of pyxis, a box) Frustules globular, solitary or in short fascia. Valve more or less hemispherical, areolate, destitute of spines. PYXIDICULA CRUCIATA EHR. Valve hemispherical, with large, hexagonal cells. An inner stratum is finely punctate. Blue clay. Walnut St. Bridge. Rare. Pl. 38, Fig. 8. This form is not usually described as having punctate areolx, but it does not apparently differ from other forms of Pyxidicula of Ehrenberg as described by Kuetzing (Species Alga- rum, pp. 21-23), including P. areolata. In fact, it differs from Stephanopyxis, which is also sometimes punctate, only in the absence of spines. In fossil deposits the absence of an easily detached stratum is not significant. The difference, except in size, between it and P. mediterranea Grun. (V. H.5., Pl. 95, Figs. 15 and 16), I am unable to determine. Although many species of Meloseira are fresh-water, the habitat of the group Melo- seirine is, in general, marine. It more nearly coincides in structure and development with other alge not diatomaceous, the siliceous envelope constituting its most distinctive feat- ure. As we proceed in the classification, the structure both of the frustule and contents becomes more complicated. (b)- COSCINODISCIN & 1. Cyclotella—Valve with two concentric divisions of different structure, one a wide border and the other a central surface. 2. Coscinodiscus.--Valve areolate or punctate, with a narrow border of the same structure. CYCLOTELLA KUETz. (1833) (cyclos, a circle) Frustules single or geminate, cylindrical, short, in zone view rectangular or with undu- lating sides. Valve usually with smooth or punctate strie, centre sometimes builose, smooth, or with granules scattered or radiating. Chromatophores numerous along the valves (Pfitzer). CYCLOTELLA STRIATA (KUETZ.) GRUN. Valve 30-80 » in diam., with coarse strie, 7-12 in 10 », centre coarsely punctate and bullose. Coscinodiscus striatus Kuetz. Cyclotella dallasiana Wm. Sm. Common in the blue clay. Pl. 2, Fig. 9. ‘ CYCLOTELLA MENEGHINIANA KUETZ. Frustule in zone view rectangular, undulated; valve, 10-20 yw in diam., marginal stria robust and transversely punctate, centre radiately punctate. Cyclotella kuetzingiana Wm. Sm. (not Thwaites). Crum Creek. PI. 2, Fig. 8. 20 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY CYCLOTE/LLA MENEGHINIANA, VAR. STELLIGERA CL. AND GRUN. Differs from the type in the coarse radiating lines at the centre. Broomall Lake, Media. Pl. 2, Fig. 4. CYCLOTELLA MENEGHINIANA, VAR. STELLULIFERA CL. AND GRUN. As in type but with the central rays granulate. Broomall Lake, Media. Pl. 2, Fig. 12. CYCLOTELLA STYLORUM (BR.?) V. H. Margin striated, the alternate strie thickened near the border, producing an appear- ance of subquadrate cells. Centre faintly granulate, the outer border of which is encircled by 10-12 puncta, each ot which is surrounded by a small hyaline space. Blue clay. Rare. Van Heurck gives this form doubtfully as a variety of striata, while De Toni makes it synonymeus with it. Van Heurck’s figure is not that of Brightwell, but as the specimen above described is, I believe, exactly the same as Van Heurck’s, I retain his name. Pl. 2,-Fig. 10. CYCLOTELLA COMTA (EHR.) KUETZ. Valve with marginal strize well marked, each third or fourth costa more robust than the others. Central part finely striated, the striz punctate, radiating. Fresh water. Pil. 2, Fig. 7. The form here figured is probably the variety radiosa Grun. and is from a New Eng- land specimen. It is quite likely to occur in this locality. CYCLOTELLA OPERCULATA (AG.) KUETZ. Frustules in zone view undulated. Angles rounded. Marginal coste alternating with minute spines; centre nearly smooth, depressed, convex or flexuose. Fresh water. Pl. 2, Figs. 5 and 6. The figure is drawn from a specimen from Boston, Mass., H. L. Smith Type Slide No. 107, marked equivalent to C. minutula Wm. Sm. CYCLOTELLA ANTIQUA WM. SM. Marginal cost alternating with thick puncta; centre finely granulate with subtrian- gular elevations. Frustules in zone view rectangular. Blue clay. Pi. 2, Fig. 11. The form corresponds to the original specimens of Wm. Smith in the deposit of Staven- ger, Norway. The genus Cyclotella comprises about seventy specific names, many of which may be referred to other genera, while some of Ehrenberg’s are incapable of verification on account of the small size of the figures and the lack of sufficient description. About half of the forms are marine. The fresh-water species are usually found living in more or less stagnant water or in pools contaminated with drainage, being an exception to the general rule that diatoms are more abundant in water free from deleterious matter. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 21 Coscrnopiscus Eur. (1838) (coscinon, a sieve, and discus) Frustules solitary, cylindrical, compressed; valve circular or elliptical; surface flat or sometimes convex uear the border; markings more or less angular, radiating, sometimes fasciculate; border usually well defined. Central space, if present, hyaline, sometimes sur- rounded with a rosette of large cells. Chrematophores round, angular or irregular discs usually without pyrenoids (Karsten). Rattray’s classification is here followed, so far as it refers to our species. Excentrict.—Valves circular; central space absent; markings angular, in oblique, decus- sating rows. Lineati—Central space absent; markings angular, oblique decussating rows straight. Fasciculati—Markings fasciculate, or sometimes only near the border. Radiati—Markings rounded or angular, more or less radiate. Elaborati.—Valves elliptical, markings rounded. EXCENTRICI COSCINODISCUS EXCENTRICUS EHR. Valve with a hyaline excentric space from which proceed, usually in six directions, rows of polygonal markings decreasing toward the narrow, coarsely striated border, the rows appearing convex toward the centre. Apiculi at unequal distances apart. Quite variable in size. Common in the blue clay and along the coast. PI. 2, Figs. 14 and 20. Fig. 20 is probably var. perpusilla Grun. (Diat. Fr. Jos. L., Pl. 4 (D), Fig. 7). LINEATI COSCINODISCUS LINEATUS EHR. Valve circular, markings hexagonal, cells in parallel rows. Border narrow, cellular. Blue clay and Atlantic coast. Not common. Pl. 3, Fig. 8. FASCICULATI COSCINODISCUS NITIDUS GREG. Valve flat, markings rounded, distant, radiate, decreasing toward the border which is coarsely striate. Quite variable in size and in the distance between the markings. Blue clay and Atlantic coast. Common. Pl. 2, Fig. 18. COSCINODISCUS NITIDULUS GRUN. Valve usually not quite circular; markings smaller than in nitidus and fasciculate near the border. Blue clay. Pl. 2, Fig. 19. Various intermediate forms between nitidus and nitidulus occur. CGSCINODISCUS SUBTILIS EHR. Markings polygonal, irregular at the centre, but forming nurnerous fasciculi radiating 22 THE DIATOMACE.® OF PHILADELPHIA AND VICINITY toward the border, the rows parallel to the central row of each fasciculus. Border narrow with fine striz; apiculi often present between the fasciculi. Blue clay and along the coast. Very common in the water supply of Philadelphia and Camden, where the diameter seldom exceeds 40 » and the markings on the semi-radius are 10 in 10 p. Pl. 2, Fig. 17. COSCINGDISCUS DENARIUS SCHMIDT Markings larger than in C. subtilis, equal, forming usually ten fasciculi, each begin- ning near the semi-radius and containing ten parallel rows of granules. Common in the blue clay and sparingly along the coast. Pl. 2, Fig. 13. Forms are found intermediate between C. subtilis and C. denarius, as shown in Fig. 15. COSCINODISCUS POLYACANTHUS GRUN. Markings angular, 10 in 10 u, decreasing toward the border, fasciculate. Apiculi large, twelve or more, usually inserted at the middle of each fasciculus, and extending into the interior of the cell. The apiculi in outline resemble the heads of horse-shoe nails, and are seen with difficulty except when the valve is examined from the inner side. Border narrow, striated. Diam. 70 pn. Pensauken, N. J., artesian well. Pl. 38, Fig. 5. . Rattray’s description of C. polyacanthus var. intermedia Grun., from Cape Wankarema, Siberia, gives the diam. as 60 », and there are about 7 markings by actual count in 10 p in Grunow’s figure (Diat. Fr. Jos. Land, Pl. 3 (C), Fig. 25). The apiculi are more numerous, but there appears to be little doubt of the general similarity. The Philadelphia form is abundant in the Pensauken well deposit at a depth of 33 ft. The apiculi become quite dis- tinct in slides stained with silver nitrate by Mr. F. J. Keeley; they are distinct from small apiculi sometimes evident between the fasciculi. The specimens in the Pensauken deposit are mingled with other forms which cannot be distinguished from C. subtilis. Whether the two are identical, I am unable to determine. Rattray (Rev. Cos., p. 47) refers to H. L. Smith’s Type Slide No. 100, from rice-field mud, Savannah, Ga., as C. subtilis. In Smith’s slide, in my possession, a number of the forms show faint outlines of the large apiculi and are otherwise exactly like C. polyacanthus. RADIATI COSCINODISCUS VELATUS EHR. Markings angular, decreasing slightly toward the coarsely striated border, covered with fine puncta. Blue clay. Pl. 3, Fig. 2. COSCINODISCUS MARGINATUS EHR. Markings rounded, large, decreasing toward the broad border, which is coarsely marked with distant strie. The cells are punctate. Common in the blue clay. Pl. 3, Fig. 9. In the fossil forms the puncta are not evident, hence the species is usually described as not punctate. THE DIATOMACE-E OF PHILADELPHIA AND VICINITY 23 COSCINODISCUS RADIATUS EHR. Markings polygonal, slightly decreasing toward the border where they are much smaller; border well marked, striate. Quite variable in size. Common in the blue clay and along the coast. Pl. 3; Fig. 11. Fig. 1 is probably a smaller form. COSCINODISCtS SUBAULACODISCOIDALIS RATTR. Markings small, decreasing toward the border in somewhat fasciculate rows. About one-third the distance from the border are five (Rattray finds six) well-marked apiculi somewhat resembling those of Aulacodiscus. Border narrow, hyaline. Rare in the lower stratum of the blue clay. Pl. 3, Fig. 4. COSCINODISCUS ARGUS EHR. Markings angular with central dots, increasing from the centre toward the border, where they are smaller. Blue clay. Pl. 3, Fig. 7 (a small form). COSCINODISCUS BIANGULATUS SCHMIDT Central space and rosette absent, markings large, angular, not punctate, with large central papille, decreasing toward the border. Border wide, coarsely marked with rows of granules, and with two indentations on the inner side distant from each other about two- thirds of the diameter. Blue clay. Pl. 3, Fig. 3. Distinguished from Coscinodiscus asteromphalus var. omphalantha Grun., which also has two constrictions, by the absence of punctate markings. COSCINODISCUS ASTEROMPHALUS EHR. Central space small, surrounded by a rosette of large polygonal cells from which radiate hexagonal cells, increasing about half way toward the border and then slightly decreasing. Cells punctate. Blue clay. Pl. 2, Fig. 16; Pl. 40, Fig. 12. COSCINODISCUS ASTEROMPHALUS VAR. OMPHALANTHA (EHR.) GRUN. Central space absent, rosette evident. Markings 214 in 10 u, somewhat smaller near the rosette and decreasing near the border, which is constricted in two places, as in C. biangulatus. Blue clay. Pl. 38, Fig. 10. COSCINODISCUS OCULUS-IRIDIS EHR. Central space and rosette distinct; markings polygonal, not punctate, with large papille, smaller near the rosette, increasing toward the semi-radius, and then decreasing to the striated border which is comparatively narrow. Blue clay and Atlantic coast. Pl. 3, Fig. 10. 24 THE DIATOMACE-E OF PHILADELPHIA AND VICINITY ELABORATI COSCINODISCUS LEWISIANUS GREV. Valves elliptical, major axis a little more than twice the minor. From a point, usually near one side, radiate rows of granules in lines nearly parallel to the major axis. Border broad, with distinct striz. Great Sedge Island, N. J. (artesian well), and in outcrops later than the Miocene, where it is usually found. Pl. 3; Fig. 5. 2. ACTINODISCEZ = ACTINOPTYCHINE Valves divided into sectors alternately elevated and depressed. -.-.-— ~~ (1) Actinoptychus.—Sectors plane. (2) Polymyxus.—Sectors convex. ActTinopTycuus Eur. (1839) em. V. H. (1890) (actis, a ray, and ptyx, a fold) Frustule cylindrical, less in length than the diameter, in zone view undulated. Valve divided into six or more sectors alternately raised and depressed, areolate and punctate, varying in the alternate divisions. The areolation is confined to the outer layer of the valve while the punctation is usually on an inner valve often found detached. Processes on the border, three or more. Umbilicus circular or angular, hyaline. ANALYSIS OF SPECIES Sectors, CIty. ..atsuseawr eeieas ess ae oka caer ene aeeeeey undulatus “Sectors, eight or more, cellular......................2.2-2005- heliopelta Sectors, fourteen, punctate............... 0.2 eee cece eee vulgaris ACTINOPTYCHUS UNDULATUS (KUETZ.) RALFS Valve areolate and punctate in quincunx, divided into six equal sectors, alternately elevated or depressed, their areolations appearing different. Margin well defined. Umbil- icus smooth, hexagonal. Processes three, sometimes six, inserted within the margin of each alternate division. Very variable in size and appearance. This is the Actinocyclus of Bailey, figured and described in Amer. Jour. Science, 1842, p. 93, Pl. 2, Fig. 11, but not named. Kuetzing describes and names it and refers to Bailey. Actinoptychus omphalopelta Ehr. Actinoptychus cellulosa Ehr., H. L. Smith Sp. Typ., 384. Quite common in marine and brackish water and in the blue clay. Pl. 4, Figs. 1, 2, 4 and 6. ACTINOPTYCHUS VULGARIS VAR. INTERRUPTA N. VAR. Valve with fourteen sectors, the alternate ones divided by a smooth lanceolate space for about one-half the radius, forming with the smooth, circular umbilicus a seven pointed star. The sectors thus divided have coarser puncta in quincunx than the other sectors, ending in a smooth area near the margin, and also larger black puncta scattered from the centre to the semi-radius. Near A. vulgaris var. neogradensis Pant. Blue clay. Not common. Pl. 4, Fig. 5. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 25 ACTINOPTYCHUS HELIOPELTA GRUN. VAR.? . Valve circular, sectors, eight, umbilicus circuiar, without rays; border wide, cellular, with distinct rays. Inserted at a distance within the inner edge of the border are large processes, one on each of four alternate sectors, and two on each of the others. The.sectors are cellulate and punctate. Near A. heliopelfa var. versicolor Brun., which, however, in the specimen in my collec- tion from Atlantic City (artesian well), has a greater number of processes and they are situated on the edge of the border. Outcrop at Buckshutem, N. J. Rare. Pl. 4, Fig. 3. It has been quite well determined, I think, that the typical forms of A. heliopelta occur at the base of the Miocene. At Rock Hall, Md., on the eastern shore of Chesapeake Bay, at a depth of from 21 to 130 ft., and at Wildwood, N. J., at a depth of from 78 to 179 ft., diatomaceous beds occur considered by Mr. Lewis Woolman (Geol. Surv. of N. J., 1898, pp. 116-121) ‘‘as synchronous in age,” the former being deposited in the Delaware River Delta and the latter in the Chesapeake in post-miocene times. In each of these beds a small form of A. heliopelta is rarely found. The material at Buckshutem is post-miocene, and the form here figured shows a marked variation from the Miocene species and a gradual approach toward A. undulatus. Potymyxus L. W. Batt. (1855) Valve circular, usually divided into fourteen sectors which are on the same plane at the centre, but the alternate ones are elevated into mammillated projections terminated by small processes on the margin. Zone view rectangular with undulations subconical, terminated by the processes. POLYMYXUS CORONALIS L. W. BAIL. Central space hyaline, rounded or slightly stellate, from which radiate rows of fine puncta in quincunx, shown in the figure only on the alternate elevations, the depressed interspaces being out of focus. The mammille are stated by Bailey to vary from six to ten. Very rare in the blue clay (Walnut St. Bridge). Occurs also in the Wildwood deposit (Bull. Torrey Bot. Club, 1895, p. 261). Pl. 4, Fig. 7, and Pl. 5, Fig. 2. 3. EUPODISCEE Aulacediscine.—Valves with mammiform elevations near the border surmounted by nipple-like processes. AULACGDISCUS—THE ONLY GENUS AS ABOVE Eupediscine.—Valves with ccelli. (1) Actinocyclus.—Valve with one small ocellus; stria radial. (2) Eupodiscus.—Valve with one or more ocelli; strix not radial. (3) Auliscus—Valve with large, elevated ocelli. Central area hyaline. Markings granulex and costate. (4) Pseudauliscus.—Valve with radiating granules. No central space. 26 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY AULacopiscus Eur. (1844) em. Ratrr. (1888) (aulax, a furrow, and discus) Valve usually circular, plane or with an elevated zone, frequently inflated beneath the processes; central space irregular or rounded, sometimes absent; markings granular, radial, sometimes in a reticulum. The genus comprises more than one hundred species most of which are fossil, and is represented in this locality by a single form, A. argus, included by Rattray in his section “Retiformes,” distinguished by the presence of a reticulum. AULACODISCUS ARGUS (EHR.) SCHMIDT Frustule in zone view elliptical. Valve circular,.125-190 » in diam., closely covered with two kinds of markings, one, a mesh of large, radiating, angular cells, the outer plate, and the other, radiating rows of circular granules with hyaline spaces intervening and closer near the border, forming the inner plate which can occasionally be seen detached. Central space absent. The walls of the angular cells are crossed with fine lines and are probably composed of granules compressed so closely as to produce partial opacity, the depth of which depends in a measure not only on the superposition of the two plates, but on the relative closeness and thickness of the cell-walls. In a fully-developed specimen the effect is to produce more or less triangular cells containing three or four granules. In some cases the opacity is so great as to render detail invisible. ‘ In the figure the valve is supposed to be divided into three sectors, illustrating at ‘‘a’”’ the lower plate, at ‘‘c’”’ the combination of the upper and lower plates, and in the other sector the cellular mesh of the upper plate. Processes, usually three, quite robust and in- serted at from one-fourth to one-fifth the length of the radius from the border which is striated on the inner side. A form with four processes is found in the lower blue clay. Tripodiscus argus Ehr. Eupodiscus argus (Ehr.) Wm. Sm. Not uncommon in the blue clay. Pl. 4, Fig. 8. . ACTINOcYCLUS Ear. (1837) (actis, a ray, and cyclos) Valve circular or elliptical; surface flat at the centre, sloping toward the border. Cen- tral space usually evident, rounded or irregular. Markings rounded, granular, punctiform, in radial, or nearly radial, rows, sometimes fasciculate. A nodule, more or less evident, is found near the border which is usually striate. Chromatophores round discs or granules. ANALYSIS OF SPECIES Valve circular, rows radial, hyaline lines at the border........ barkleyi Valve circular, rows fasciculate...............0000¢ 00 eee ae moniliformis Valve GUiptital:. soe+dcxseyciwaes nous orn eo twie ree ellipticus The nodule is generally supposed to be a thickening of the cell-wall, and, in the opin- ion of Rattray, a projection outward, but ‘‘whether there may not be at the same time a slight inward protuberance is difficult to determine,” though, as a rule, he seems to ‘‘think there is not.” THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 27 ACTINOCYCLUS BARKLEYI VAR. AGGREGATA RATTR. Surface flat from centre to semi-radius. Central space irregular, sometimes with a few scattered granules. Markings round with central dots distinct, about 7 at the centre, de- creasing in straight radial rows to 12in 10 pat the border, where they form moniliform striz. Border narrow with striz about 16in 10. Hyaline interspaces at the origin of the shorter rows, but not at equal intervals. At the border, linear hyaline spaces occur at somewhat irregular intervals between the moniliform strize owing to the termination of certain radial rows before they reach the circumference. Nodule small, from one-seventh to one-fourth the radius from the border. According to Rattray the distinction between A. ralfsii and A. barkleyi is partly in the absence of the zone arrangement of the hyaline spaces in the latter, and to the slight dif- ferences in the number of granules. The variety aggregata differs from the type form of barkleyi mainly in the distance of the nodule from the border. I have specimens from the blue clay material at Walnut St. Bridge, and from Smith’s Island, in which the distance from the border in one case is, as stated above, quite different from that in the other. In specimens from Morris Cove, Conn., the locality referred to by Rattray, variations occur. Blue clay. Pl. 6, Fig. 1. In the figure the subulate hyaline spaces at the border are, in some instances, wider than usual. ACTINOCYCLUS MONILIFORMIS RALFS Surface flat, from centre to about five-sixths of the radius. Central space rounded, with one or more granules. Markings, 8 in 10 », round, in radia! rows, fasciculate, the oblique transverse rows irregular, very slightly decreasing until near the edge of the flattened zone, and then suddenly decreasing and appearing as decussating lines oblique to the border. Apiculi distinct, interfasciculate within the border. Nodule quite evident, surrounded by a rather wide irregular hyaline space on the margin of the flattened zone in the middie of the fasciculus. Border wide, with strie about 20 in 10 u. Blue clay. Port Penn. Not common. Pl. 6, Fig. 2. Equivalent to Actinocyclus chrenbergii, H. L. S. Type Slide 10. In a valve from Port Penn, Delaware Bay, two nodules occur nearly opposite each other. ACTINOCYCLUS ELUIPTICUS VAR. DELAWARENSIS N. VAR. Valve rhombic-elliptical. Markings somewhat angular, 6 in i0 4 at the centre where they are sub-concentric, thence decreasing in lines radiating more or less toward the bor- der, where they suddenly become punctiform, stria about 20 in 104. Border equal to one- fifth the radius. A nodule is found on the inner side of the border. Apiculi apparently absent. The markings are larger than in the Richmond forms which are associated by Rattray with Actinocyclus ellipticus Grun. The form corresponds closely to Witt’s Cestodiscus ovalis var.? (Witt, Polirschief. von Archangelsk-Kurojedowo, Pl. 8, Fig. 2), except as to the border. It does not answer to Van Heurck’s figure or any other. Blue clay. Very rare. Pl. 3, Fig. 6. 28 THE DIATOMACE.® OF PHILADELPHIA AND VICINITY Evpopiscus Eur. (1844) (eu, well, pous, a foot, and discus) Valve circular, 45-117 » in diam. (De Toni). Central space absent, surface plane with angular cells. At the border short, circular processes or ocelli. EUPODISCUS RADIATUS BAIL. ~ = Valve with radiating hexagonal cells, sometimes slightly curved toward the large ocelli inserted near the border which are hyaline at the centre. Border wide, coarsely striate. The number of ocelli heretofore recorded is four. Specimens with five processes are found in the artesian well at St. Augustine, Fla., and in material at Twelfth and Brandy- wine Sts. Mr. Hugo Bilgram has discovered valves with three and six ocelli. Not common in the blue clay, but abundant along the southern coast of the Atlantic states and the Gulf of Mexico. Not Eupodiscus radiatus Wm. Sm, which is Biddulphia smithii (Ralfs) V. H. P1. 5, Fig. 3. AuLiscus Exp. (1843) (aulax, a furrow, referring to the grooves in certain species, according to De Toni, but preferably from auliscos, a small reed, referring to the processes?) Frustule cylindrical; zone with longitudinal rows of fine puncta. Valve circular or elliptical, plane except near the processes; central area hyaline, usually circular. Markings of two kinds, granules radiating or scattered and radiating, costate lines, prominent or indistinct. Processes, two or three, large, short, cylindrical, with hyaline surface, near the ends of the major axis in a line oblique to it. Auliscus is divided by Rattray into fourteen sections, defined chiefly by the character and arrangement of the markings. About eighty species are described, but as many of the forms are fossil, occuring in the Miocene of California, Oamaru and elsewhere, and as so few species are found in this locality, I shall refer but briefly to this division. Striolatt.—No transverse median areas, striz incenspicuous...... punctatus Lineolatii—Markings distinct, pruincse, -interrupted.......... pruinosus Costati.—Transverse median areas usually distinct, markings continuous, costate ....... 0... ccc cece eens { sculptus celatus AULISCUS PUNCTATUS BAIL. Valve broadly elliptical, or suborbicular, covered with delicate interrupted striz radiat- ing in sinuous lines to the circumference, more evident on the transverse median area; puncta 3 in 10 uz, grouped into a rounded area on each side of the median line, elsewhere scattered. Central space rounded, processes two, large, suborbicular. Port Penn, Delaware River. Rare. Pl. 5, Fig. 6. AULISCUS PRUINOSUS BAIL. Valve elliptical, with distinct, interrupted, pruinose, irregular markings diverging in curved lines toward the circumference in the median part and converging toward the proc- esses, interspersed with numerous darker markings having the appearance of apiculi. Cen- tral space nearly circular, sometimes with several granules. Processes large near the ends of the major axis and not cblique to it, or scarcely so, the edges with a crenulate border. Blue clay. Rather rare. Pl. 5, Fig. 2. THE DIATOMACE-E OF PHILADELPHIA AND VICINITY 29 AULISCUS SCULPTUS (WM. SM.) RALFS Valve elliptical or subcircular, median areas distinct, rounded, circumscribed by coarse distant cost radiating near the border where they are more evident, and converging to- ward the processes. Central space rounded, sometimes indefinite. Processes, two, circular. Typical specimens show wide, coarse, distant coste, but, in some cases, the median areas are indistinctly outlined. Blue clay. Pi. 5, Fig. 5. AULISCUS CELATUS BAIL. Valve elliptical or subcircular, with radiating cost, more evident around the median areas and at the border, converging toward the processes, with intermediate punctate radiating lines. Central space rounded or irregular. Processes circular. A. sculptus has coarser cost and the interspaces are hyaline, or apparently so, while in A. celatus the punctate stria between the cost are more evident. Blue clay. Not uncommon. PI. 5, Fig. 4. Fig. 7 is a small, indefinite form intermediate between A. sculptus and A. celatus. The numerous variations in this genus make it difficult to satisfactorily differentiate the species. The size of the four above described varies from 40 to 150 yp. Psecnatuiscts A. S. (1875) anp LEUDUGER-FORTMOREL (1879) Valve circular or subcircular, nearly flat or depressed at the centre. Central space not evident. Processes circular, with narrow border, near the circumference. Border narrow, striated. Markings granular, radiating, sometimes interspersed with strize and apiculi. Differs from Auliscus chiefly in the absence of a central space and costa. -- PSEUDAULISCUS RADIATUS (BAIL.) RATTR. Valve circular, or nearly so, flat. Central area with scattered granules radiating and increasing in size outward in diverging rows toward the border which is coarsely striated, Processes, two, circular. Two small apiculi are inserted at about one-fifth the radius from the border near the ends of the minor axis. Blue clay. Rare. Pl. 5, Fig. 9. The apiculi are not always figured. They appear in a number of specimens from the Miocene of Maryland, Atlantic City, Harvey Cedars and Newbern. PSEUDAULISCUS SPINOSUS (CHRISTIAN) RATTR. Valve subcircular or slightly quadrangular, depressed at the centre and rising to an elevated zone near the border, the two zones separated by a distinct line. The inner zone indistinctly reticulate with fine puncta radiating from the centre and apiculi at intervals. The outer zone with smaller apiculi surrounding the inner zone and with intermingled rows of fine puncta and interrupted diverging stria. Near each end of the minor axis is a rather long, robust spine inserted at ore-fourth the radius from the border | which is narrow and striated. Processes circular, close to the circumference. Auliscus spinosus Christian. Blue clay. Rare. Pl. 5, Fig. 10. The genus is named by Schmidt, described by Leuduger-Fortmorel and emendated by Rattray. 30 THE DiATOMACE.E OF PHILADELPHIA AND VICINITY BIDDULPHIOIDEZ BIDDULPHIEX (a) Triceratiine.—Frustule cylindrical or prismatic, with three or more sides. (b) Biddulphiine.—Frustule cylindroid; valve with ends elevated into round proc- esses or long horns. (c) Anaulee.—Valve elliptical, lunate or triangular, with jnternal septa. (d) Euodiee.—Frustule cuneate in zone view; valve lunate. (a) TRICERATIINZ (1) Ditylum.—Frustule imperfectly siliceous. Zone with numerous divisions. Valve with central spine. (2) Trinacria.—Processes with sharp spines. Ditytum Batt. (1861) (dis, two, and tyle, a swelling, referring to the outline of the frustule) Frustule quadrangular, convex at the ends. Valve triangular, with undulating sides, the angles ending in a sharp point surmounted by a bristle. Surface of valve convex at centre from which projects a long stout spine. DITYLUM INTRICATUM (WEST) GRUN. Valve with the angles separated from the central part by lines imitating septa. Sur- face with radiating lines. of fine puncta. Blue clay. Rare. Pl. 6, Fig. 4. Detached valves only have been found in the blue clay. The form is regarded as but slightly siliceous and, therefore, the zone or girdle not being found in the fossil deposits, I am unable to illustrate it from material in the vicinity. On Plate 38, Figs. 6 and 7, I have sketched the zone and valve views of specimens found recently at Vera Cruz and labelled by H. L. Smith Triceratum intricatum West. I can find no difference between the recent ard fossil forms of the valves. The zone is covered with fine puncta in quincunx, not visible under ordinary illumination. The form as figured in Plate 6 corresponds to the figure of Lithodesmium undulatum Ehr. in Van Heurck, and West, in describing the Triceratium undulatum Wm. Sm. (figured as T. striolatum), thought that his T. intricatum was distinct from Ehrenberg’s form on the ground that the latter came from the ‘‘Bermuda” (Nottingham) earth and must be strongly siliceous. Lithodesmium is characterized by the envelopment of the frustules by a cellular membrane which does not appear, evidently, in Ditylum. D. brightwellii is distin- guished by its crown of spines on the margin; otherwise it closely resembles D. intricatum. Trinacria Hers. (1863) (treis, three, and acra, a point) Valve triangular, angles elevated into spines. Cells at the margin large. TRINACRIA PILEOLUS (EHR.) GRUN. Vaive with concave sides. Surface concave with unequal punctiform and scattered markings with central dots. Cells av the margin large, rounded. At the angles, which vary in elevation, a few puncta are seen. Triceratium pileolus Ehr. Blue clay. Rare. Pl. 6, Fig. 9. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 31 (b) BIDDULPHIINA BippuLPH1a Gray (1831) em. Van HeEtrck (1885). (a genus, constituted from Conferva biddulphiana of the English Botany, named after a Miss Biddulph) Frustule prismatic or subcylindrical, concatenate, filamentous, or in zig-zag, or, as usually found, free. Zone well developed. Valve triangular, polygonal, elliptic or subcir- cular, convex, more or less elevated at the angles into processes or horns. Markings cellu- lar or punctate. Chromatophores, small plates of various forms. KEY TO THE SPECIES Valves: costatess s.eo8cie heise Sia Sees cbdcy Gb nels ne we biddulphiana Valves not costate: Markings cellular, angles elevated into horns ..... Neercene favus angles not elevated ................. antediluviana Markings punctate, angles with subconical processes ait IGNE SPINES ese vans sec ddincs week oie omen granulata SPIES SUGM a cu. acetuyateteere asus -eueOReeaues rhombus SpUICS PUNULG oo 5Sseer eer aniaceaesbreok Wilstasm eeceinbe smithii processes truncate, valve elliptical.................. turgida valve orbicular .................. levis processes absent, valve divided by irregular lines ...... _alternans not so divided ........... 0... cece e ccc ee eee e eens reticulum BIDDULPHIA BIDDULPHIANA (SMITH) Frustule quadrangular with convex ends and rounded angles. Valve elliptical with undulated sides, divided by septa into three or more sections. Processes large, rounded, globular or subconical. Zone varying in width. Surface with rounded reticulations in lon- gitudinal and transverse rows, except at the centre where they are concentric and smaller. Conferva biddulphiana Smith (English Botany, 1807, Pl. 1762, upper figures). Diatoma biddulphianum Ag. Biddulphia pulchella Gray. Blue clay. Hoboken Tunnel. Along the coast. Pl. 7, Figs. 1, 2, 3, and 4. Quite variable in size and nuinber of septate divisions. Fig. 3 is an unusual form with narrow zone, having but one row of large reticulations, evidently a young frustule. BIDDULPHIA FAVUS (EHR.) V. H. Frustule quadrangular, elevated at the angles into subconical processes oblique to the longitudinal axis. Valve triangular or quadrangular, plane, of two layers, the outer layer composed of large hexagonal cells in rows parallel to the sides, the inner of small puncta radiating from the centre. Zone punctate in quincunx, never found open. Triceratium favus Ehr. Blue clay. Common along the coast. The quadrangular form occurs only southward. Pl. 6, Fig. 6. At “‘a” a cell showing the lower punctate layer. PI. 40, Fig. 16, a trans- verse section cf a portion of the valve showing the cellular structure and the punctated lower stratum. 3 32 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY BIDDULPHIA ANTEDILUVIANA (EHR.) V. H. Frustules quadrangular, sometimes united in zig-zag chains. Valve quadrangular with more or less concave sides, sometimes cruciform. Surface with angular cells arranged in concentric and radiating lines increasing toward the circumference. At each angle is a large, rounded process, which, as well as the secondary layer, scarcely visible, is finely punctate. Amphitetras antediluviana Ehr. Amphitetras tessellata Shad. Blue clay. Rare. Pil. 6, Fig. 3. A cruciform variety occurs at Pensauken, N. J., artesian well (Coll. F. J. Keeley). BIDDULPHIA GRANULATA ROPER Valve elliptical-lanceolate, convex, with diagonal rows of puncta 12 in 10 » and some- times with small scattered spurs. Processes inflated at the base, obtuse at the ends, which are curved outward toward alternate sides. Near each process and on opposite sides of the longitudinal axis is placed a stout spine bent or curved inward near the middle. Connec- tive zone with diagonal rows of puncta smaller than those on the valve. . Pavonia, N. J., artesian well. Fossil in the Pleistocene. Along the coast. Not com- mon. Pl. 7, Fig. 6. BIDDULPHIA RHOMBUS (EHR.) WM. SM. Valve rhomboidal, sometimes triangular, with subconical processes. Surface convex with hexagonal reticulations, 7-9 in 10 y, irregular at the centre and radiating to the circum- ference. Minute spurs are scattered over the surface, and on each side are usually two or three short spines. Common along the coast and fossil in the Miocene and later deposits. Pl. 7, Fig. 5 (somewhat inclined, as usually seen). BIDDULPHIA SMITHII (RALFS) V. H. Valve orbicular, convex, with reticulations 5 in 10 » radiating from the centre and decreasing toward the margin and processes which are truncate. A short spine is found on each side half way between the processes. Zone narrow with fine puncta 12 in 10 p in lon- gitudinal rows. Cerataulus smithii Ralfs. Eupodiscus radiatus Wm. Sm. Blue clay. Along the coast southward. Pl. 7, Fig. 8. BIDDULPHIA TURGIDA (EHR.) WM. SM. Valve elliptical or orbicular, surface convex. Processes very large, cylindrical, placed obliquely and inclined by the torsion of the frustule. Between the processes are two stout spines, one on each side, frequently forked at the enus. Puncta fine, irregular at the centre and radiating toward the circumference. Cerataulius turgidus Ehr. Blue clay. Along the coast. Quite variable in size. Pl. 7, Fig. 7. THE DIATOMACE.£ OF PHILADELPHIA AND VICINITY 33 BIDDULPHIA LEVIS EHR, Valve suborbicular. or triangular, with short, truncate processes. Surface with fine puncta about 13 in 10 » radiating in straight or curved lines toward the circumference and with fine spurs at intervals. Nearer one process than the other, and about half way between centre and circumference, are two smail spines, one on each side. Quite variable in size. Blue clay. Common along the coast. Pl. 7, Fig. 9. Fig. 10 (magnification about 260 diameters only) illustrates sporangial frustules dis- covered by Mr. T. Chalkley Palmer at Reedy Island, Delaware River. In frustules having a cylindrical form, the endochrome lines the cell-walls in the form of granules which become congregated toward the centre in the sporangia. BIDDULPHIA ALTERNANS (BAIL.) V. H. Valve triangular or, rarely, quadrangular, with sides straight or slightly concave, usually unequal. Angles obtuse, separated from the centre by costate lines. Surface with puncta of irregular shape, large at the centre, with smaller puncta interspersed. In many valves several lines appearing like cost extend inward froin the border in various direc- tions. Angles with small puncta in transverse and longitudinal rows. Triceratium alternans Bail. Blue clay. Along the coast. Pl. 6, Fig. 7 and probably Fig. 8. BIDDULPHIA RETICULUM (EHR.) _Frustule quadrangular. Valve triangular with straight or concave sides and rounded angles. Surface convex at the centre and angles. Markings of unequal size, mostly larger at the centre, scattered; at the angles, small puncta in longitudinal rows. Triceratium sculptum Shad. Triceratium punctatum Br. Triceratium obtusum Br. For explanation of the synonymy see ‘“‘Biddulphoid Forms of N. A. Diat.,” Proc. Acad. Nat. Sci., 1900, p. 724. Blue clay. Along the coast. Pl. 6, Fig. 5. (c) ANAULEZ EvnoToGRaMMA WEISSE (1854) (eu, well, noton, a back, and gramma) Frustule quadrangular. Valve elliptical or lunate divided by septa which constrict the margin. Surface flat with punctate markings. EUNOTCGRAMMA L.EVE GRUN. Valve lunate with obtuse ends. Septa, from four to eleven or more. Surface with puncta in transverse and longitudinal rows, sometimes indistinct and scattered. Shark River. Rare. More common southward. Fossil at Buckshutem, N. J. Pl. 7, Fig. 11, and Pl. 10, Fig. 15. I am unable to distinguish between E. leve and E. debile, as intermediate forms occur. 34 THE DIATOMACE OF PHILADELPHIA AND VICINITY TERPSINOE EHR. (terpsinoos, gladdening?) Frustules quadrangular, adnate in filaments, usually free. Valve elliptical or triangu- lar, with undulating sides divided by septa into three or more sections. TERPSINOE AMERICANA (BAIL.) RALFS: Valve lobed'at each end or angle. Central space rounded, hyaline. Surface with fine puncta in radiating lines. = 5 Blue clay. Not common. PI. 6, Fig. 10. TERPSINOE NOVE-CESAREEX BOYER Valve triangular, with concave sides and broad angles equally three-lobed, separated from the central part by septa. Central space small or absent. Puncta delicate, radiating or scattered. L. of side 62 u. Pleistocene clay at Buckshutem, N. J. Fossil at Wildwood, N. J. T. americana, forma trigona Pant.? (Le Diatomiste, Vol. 2, p. 207.) Pl. 6, Fig. 11. (dq) EUVODIE/ Evopta Batt. (1860) (derivation uncertain; apparently from euodia, fragrant, probably a euphemism) Frustule in zone view cuneate. Valve semi-lunate, coscinodiscoid. EUODIA GIBBA BAIL. Valve with rounded markings, larger and scattered at the centre, radiating at the cir- cumference and in indefinite straight rows at the semi-radius. Delaware Bay (Mann). Pl. 5, Fig. 1. I have not seen this in the Philadelphia material. The figure is drawn from a speci- men from the Gulf Stream, S. Atlantic. - PENNATE Valve zygomorphous. Structure pinnate, not concentric. Valve divided either by a true raphe or cleft or by a linear space or line imitating a raphe. Divided into three Groups: 1. Fragilarioidee.—Valves without a raphe; usually with a pseudoraphe or median line. 2. Naviculoidee—Either one or both valves with a true raphe. 3. Surirelloidee.—Valves in which the raphe is concealed near the margin on one or both sides of each valve in a more or less elevated keel or wing. FRAGILARIOIDEE _ (a) Tabellariee.—Valve symmetrical with respect to both the longitudinal and trans- verse axes; septate, not cuneate. (b) Meridionee.—Valve symmetrical with respect to the longitudinal axis, asymmetri- cal to the transverse axis, cuneate, finely striated. (c) Fragilariee.—vValve of varied shape, not cuneate; costate or with transverse rows of puncta. (a) TABELLARIE Frustule in zone view rectangular, in valve view linear or linear-elliptical, sometimes constricted in the middle, symmetrical to both axes, not cuneate; with two or more septa or annuli. Chromatophores numerous, granular. Rhabdonema.—Frustules with numerous septate partitions having one or several foramina. Transverse coste or rows of coarse puncta. Tabellaria.—Frustules with two to six nearly straight septa. Transverse strix subtly punctate. Grammatophora.—Frustules with two sinuate perforate curved septa. Transverse strie subtly punctate. Striatella.—Frustules with alternate partitions, septate or partly so. Attheya.—Frustules not septate but with numerous annuli. RHABDONEMA KUuETz. (1844) (rhabdos, a rod, and nema, a thread) Frustules quadrangular, concatenate, composed of numerous septate partitions with transverse costz or rows of puncta. Valves elliptical, with a pseudoraphe and transverse apparent costze and punctate lines; the partitions with one or several foramina. Chromatophores in rosettes of various kinds (Karsten); usually parallel to the septa. RHABDONEMA ARCUATUM (LYNG.) KUETZ. Valve hyaline at the ends, with transverse rows of puncta producing the appearance of costze between the rows; pseudoraphe distinct; foramen single. Diatoma arcuatum Lyngbye. Common along the coast. Pl. 8, Figs. 1, 2, and 3; Pl. 40, Fig. 10. 36 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY According to T. H. Buffham (Jour. Quek. M. C., Series 2, Vol. 2, p. 131), the frus- tules are of two kinds, those in which the length and breadth are the same and those which are much lengthened, with a wide hyaline girdle frequently in the middle. At the time of fructification the smaller frustules are attached to a larger one which produces a sporan- gium at the end of the girdle from which the other end of the frustule has disappeared, or, if the two halves of the frustule remain, two sporangia are formed. RHABDONEMA MINUTUM KUETZ. Frustules small; valve not smooth at the ends, elliptical or lanceolate-elliptical, with transverse rows of puncta; pseudoraphe distinct. Foramen single, alternating above and below in adjoining partitions. Common in the blue clay and along the coast. Pl. 8, Fig. 7 and Pl. 38, Fig. 11. RHABDONEMA ADRIATICUM KUETZ. Valve linear-lanceolate, with smooth angles; rows of puncta transverse, the intervals appearing as costs, as in arcuatum. Foramina, three. Blue clay in the Pensauken and Pavonia deposits and along the coast. Pl. 8, Figs. 4, 5 and 6. TaBELLARIA Eur. (1839) (tabella, a tablet) Frustules quadrangular, adnate in filaments, frequently found in zig-zag chains, united by a gelatinous isthmus, at length separating. Valve linear, inflated in the middle and at the ends; strie# transverse. Chromatophores numerous, small, along the zones. TABELLARIA FENESTRATA (LYNG.) KUETZ. Valve elongated; pseudoraphe narrow; transverse strie faint. In the zone view a straight septum is shown at each end of a valve.. Common, especially in the cedar swamps and ponds of the Pine Barren region, N. J. Pl. 8, Figs. 11 and 12. TABELLARIA FLOCCULOSA (ROTH) KUETZ. Valve linear, with median inflation larger than the terminal; pseudoraphe rather broad in the middle; transverse strix subtly punctate. In zone view the frustules are quadrangu- lar, or nearly so, with about six sometimes curved septa at one end alternating with those on the other end. Conferva flocculosa Roth. Common especially in the Pine Barrens of New Jersey. Pl. 8, Figs. 8, 9 and 10. GRAMMATOPHORA Eur. (1840) (from gramma, a letter, and phoreo, I bear) Frustules quadrangular, adnate, in zig-zag, united by an isthmus, or, usually, found free; divided by two sinuate and perforate curved septa. Valve linear or oblong, sometimes with sinuate sides, and with a pseudoraphe and transverse punctate lines. Chromatophores granular. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 37 GRAMMATOPHORA MARINA (LYNG.) KUETZ. Valve linear-elliptical, with smooth apices. Septum with a wide undulation near its origin, thence straight and incrassate at the end. Strie in quincunx, 18-21 in 10 uw. Diatoma marinum Lyngbye. Blue clay. Along the coast. Pl. 8, Figs. 17 and 18. GRAMMATOPHORA MARINA VAR. SUBTILISSIMA (BAIL.) Vv. H. Valve linear, slightly constricted near the smooth apices. Septum undulated near its origin and then straight, incrassate at the end. Puncta in quincunx very subtle, 34-36 in 10 wu. Grammatophora subtilissima Bail. Grammatophora oceanica var. subtilissima (Bail.) V. H., according to De Toni. G. marina and G. oceanica are united by some authors; the latter has more subtle striz. Along the coast. Pl. 8, Figs. 13 and 14. GRAMMATOPHORA SERPENTINA RALFS Valve linear-elliptical, long, measuring to 150 » (De Toni); smooth at the apices. Sep- tum with numerous undulations and hooked at the apex. Puncta in quincunx, 17 in 10 p. Along the coast. Pl. 8, Fig. 21. GRAMMATOPHORA ANGULOSA VAR. HAMULIFERA (KUETZ.) GRUN. Frustule nearly quadrate; valve with rounded but not smooth apices. Septum bent into a sharp angle near its origin and ending in a broad hook. Puncta in transverse rows, 14in 10 gp. Along the coast. Pl. 8, Figs. 15 and 16. GRAMMATOPHORA ISLANDICA EHR. Frustule oblong; valve elliptical-lanceolate. Septum robust with several undulations and hooked at the end. Pseudoraphe distinct; transverse rows of puncta, 10 in 10 n. Reported by Kuetzing in the Atlantic Ocean and by Kain at Belmar, N. J. [have not found it on our coast and I believe, in some cases, it has been confused with G. angulosa var. hamulifera. The figure is drawn from an Iceland form in H. L. Smith T. S., 186. Pl. 8, Figs. 19 and 20. STRIATELLA Aa. (1832) (dim. of stria, referring to the lines on the frustule) Frustules tabulate, adnate in short, stipitate filaments, scarcely siliceous, divided into partitions, septate or partly so at alternate ends. 38 THE DIATOMACE OF PHILADELPHIA AND VICINITY STRIATELLA UNIPUNCTATA (LYNG.) AG. Frustules with numerous bent septa extending the entire length. Vaive lanceolate, somewhat unsymmetrical, subtly punctate, with pseudoraphe quite distinct. “The specific name is derived from the appearance of the endochrome which in the living specimen is invariably collected in a central mass with slender threads radiating in all directions toward the cell-wall’”’ (Wm. Sm.). Pyrenoids cuneate, in the centre of the endochrome, numerous. Long Island Sound and along the coast. Pl. 8, Figs. 22 and 23.. STRIATELLA INTERRUPTA (EHR.) HEIB. Frustules quadrangular, with robust alternate septa extending to the middle. Puncta in quincunx, 22 in 10 pz. Tessella interrupta Ehr. Very rare along the coast. Tl. 8, Fig. 24. (From a form found at Stonington, Conn.) AtTHEeyA West (1860) (named after Thomas Atthey) Frustules quadrangular, tabulate, with numerous annuli. Valve elliptical-lanceolate, with a pseudoraphe and a central punctum. Extending from each end is a strong spine half as long as the valve. ATTHEYA DECORA WEST The only species. Diagnosis of the genus. The valves are imperfectly siliceous, scarcely visible in balsam. Very local. Abundant at Shark River, N. J. Pl. 8, Fig. 25. y (b) MERIDIONEE Valve symmetrical in zone and valve view along the sagittal line, but asymmetrical to the transverse axis, cuneate. In zone view sometimes with wedge-shaped septa. Valve finely striated, without central and usually without terminal nodules; a pseudoraphe present. Licmophora.—Frustules cuneate in stipitate fan-shaped fascicles. Meridion.—Frustules cuneate in spiral fascicles. LicmopHora AG. (1827) (liemos, a fan, and phoreo, I bear) Frustules wedge-shaped, joined together into fan-shaped, stipitate fascicles. Valve cuneate, rounded at both ends, septate. Chromatophores granular, round or oval in our species. THE DIATOMACE-E OF PHILADELPHIA AND VICINITY 39 ANALYSIS OF SPECIES (In accordance, so far as it relates to our species, with the classification of C. Mereschkowsky, Diagnoses of New Licmophore, Nusva Notarisia, 1901.) Placate—valve narrow, stri# very fine, septa superficial. ..... flabellata Dubie—valve bacilliform, septa shallow, frustule with thick Walls ecu hoce tanec sist eine sb achas Ab mer uid maw eoerine Haren ovulum Paradoxee—valve with lower end produced, strie fine, pseudo- —— Tape distinct, septa. C6epi cco dece cosd vewinei gen dae wes paradoxa gracilis tincta baileyi ? Lyngbyeex—valve narrow, attenuated at both ends, distinct, Septa Gecpsacsck fondest sre omer ee eae aes lyngbyei Peristriate—valve broad, pseudoraphe wide, strie robust .... ehrenbergii LICMOPHORA FLABELLATA (CARM.) AG. Frustule elongate, narrow; valve narrow, lanceolate-cuneate, enlarged at the base; strie very fine, 30 in 10 z. Echinella flabellata Carm. Licmophora splendida Wm. Sm. Common along the coast. Pl. 9, Figs. 1 and 2. LICMOPHORA OVULUM MER. Valve ovate, attenuated to the rounded inferior apex; pseudoraphe indistinct, striae fine, 24in 104. Zone view broad, cuneate, angles rounded, inferior apex broad; frustule robust, septa superficial, straight. (Mereschkowsky, in part.) Atlantic City. Common. Pl. 9, Figs. 8 and 9. LICMOPHORA PARADOXA (LYNG.) AG. Frustule broad, with rounded angles; septa curved; valve ovate, inferior apex produced. Pseudoraphe distinct; strie varying from 25 below to 30 above in 10 uz. Echinella paradoxa Lyng. PRhipidophora -paradora Kuetz. Along the coast. Pl. 9, Figs. 6 and 7. LICMOPHORA GRACILIS (EHR.) GRUN. Frustule cuneate, narrow, with sinuate margin; valve clavate, linear at the base; strie, 20 to 22 in 10 n. New Rochelle. Along the coast. Pl. 9, Fig. 11. LICMOPHORA GRACILIS VAR. ELONGATA (KUETZ.) DE TONI As in the type, but more graceful and with deeper septa. Rhipidophora elongata Kuetz. Along the coast. Not common. Pl. 9, Figs. 12 and 13. 40 THE DIATOMACEE OF PHILADELPHIA AND VICINITY LICMOPHORA TINCTA (AG.) GRUN. Frustules cuneate, narrow, usually found in twos. Valve clavate, hyaline, rather broad at the base; septa moderately deep; pseudoraphe indistinct; stria, 27 at the base, 30 in the middle and 33 at the apex in 10 u. Gomphonema tinctum Ag. Along the coast. Abundart from abvut the middle of July to the middle of August. Pl. 9, Figs. 14 and 15. LICMOPHORA BAILEYI (EDW.) GRUN. Frustule broadly cuneateor with convex margins, rarely almost orbicular; valve spat- ulate or ovate with slender, produced base; septa very deep; pseudoraphe distinct; stria ~~~ 20 in 10 x. Podosphenia baileyi (Edw.) Lewis. Long Isiand Sound and upper coast of New Jersey. This form is placed in a doubtful position by Mereschkowsky. As it corresponds more closely to the Paradoxe, it is placed here provisionally. The girdle face and apex of the valve are round, the pseudoraphe is distinct and the septa deep, but the stipe is short. Pl. 9, Fig. 10 and Pl. 38, Figs. 3 and 4. LICMOPHORA LYNGBYEI (KUETZ.) GRUN. Frustule cuneate, slightly rounded at the angles. Valve oblanceolate; pseudoraphe distinct; septa deep; stria, 12 in 10 u below, and 16 in 10 u above. Podosphenia lyngbyet Kuetz. Along the coast. Pl. 9, Figs. 3 and 4. LICMOPHORA EHRENBERGII (KUETZ.) GRUN. Frustule cuneate, broad. Valve obovate-lanceolate; pseudoraphe wide; strie coarse, 8 in 10, moniliform. Podosphenia ehrenbergit Kuetz. Along the coast. Pl. 9, Fig. 5. Mention Aa. (1824) (merizo, I divide) Frustules in zone view cuneate, adnate in circular or spiral fascie, at length becoming free. Valve symmetrical with respect to the longitudinal axis, more or less cuneate; cost and striz transverse. Chromatophores numerous, small, elongated, in irregular rows on the zone (Pfitzer). MERIDION CIRCULARE (GREV.) AG. Transverse coste coarse, variable in number and distance apart, sometimes inter- rupted or indistinct; strie interstitial, 16 in 10 p. In springs and small streams of pure water. Echinella circularis Grev. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 41 Meridion constrictum Ralfs, sometimes given as a variety of M. circulare, differs only in the constriction below the apex. The two kinds of frustules are usually found growing together and as the variation is often extremely slight they are here included under the earlier name. Pl. 10, Figs. 1, 2 and 3. Fig. 1 represents the constricted form which is the more common. Fig. 3 is a sporangial form. The sporangial frustules vary in shape and size, some being long and slender, others clavate, but they are all more or less tumid in the middle, with costa more indefinite than in perfect valves. All gradations occur, one end becoming shorter until the valve has the shape of the variety known as constrictum. It would seem, therefore, that the non-con- stricted form is a passage from the sporangial to the smaller or adult form, or is of no spe- cific importance. All forms are found living together. The adult frustules are the smaller ones; it is from them that the sporangia are produced. Meridion intermedium H. L. Smith (Amer. Quart. Mic. Jour., Vol. 1, p. 12) is char- acterized by less evident coste and is more delicate in general appearance. Some forms are capitate and others are not. Prof. Smith compares the M. intermedium with Peronia erinacea Bréb. and Arnott which he has named M. erinaceum, hitherto found only in Europe, and points out the relation of the two ferms to Licmophora. An examination of the H. L. S. type slides of the two diatoms proves that Peronia has very delicate cost and a distinct pseudoraphe not noticeable in Meridion. On the slide of Peronia are frustules exactly similar to certain of the sporangial variations of M. circulare. The fan-like arrangement of Licmophora, the marine form, and the circular chains of Meridion, the fresh-water genus, are similar. Both are stipitate at the beginning of their growth. (c) FRAGILARIEZ Divided into three sections: Diatomine.—Valve circular, elliptical to linear, quadrate or cruciform, with transverse cost; without raphe, a pseudoraphe sometimes wanting. Fragilariine.—Valve elongate, with small central and terminal elevations, without coste but with transverse punctate striz; without genuine central nodule. Eunotiine.—Valve lunate; a raphe sometimes partially formed with terminal nodules near the edges. DIATOMINZ Diatoma.—Frustules in filaments. Valve linear or elliptical, costate. Plagiogramma.—Frustules in fascie or free. Valve costate. Opephora.—Valve costate, with an inner punctate stratum. Dratoma DE CANDOLLE (1805) em. Hers. (1863) (diatemno, I cut in two) Frustules oblong or quadrate, adnate in filaments, attached by alternate angles and finally separating. Valve linear or elliptical, with, transverse cost and rows of puncta and a pseudoraphe. Chromatophores large granules without definite arrangement. (See PI. 40, Fig. 11.) 42 THE DIATOMACE.& OF PHILADELPHIA AND VICINITY DIATOMA VULGARE BORY. Valve elliptical-lanceolate, with apices sometimes rostrate or capitate; pseudoraphe narrow; cost2, 5 in 10 p. Common everywhere in pure fresh water and extremely variable. Pl. 10, Figs. 9 and 10. Var. elongatum (Ag.) = var. ehrenbergii (Kuetz.)—elliptical-lanceolate, constricted near the apex. Var. grande (Wm. Sm.) Grun.—linear, elongated, constricted near the apices. Pl. 10, Fig. 4. Both of these varieties, with numerous intermediate forms, are abundant near New- town Square. Varieties of Grunow, known as breve, ovate-lanceolate; productum, ovate- lanceolate with produced apices; capitulatum, lanceolate with capitate extremities, are mingled together in the same gathering. DIATOMA ANCEPS (EHR.) KIRCHN. Valve linear with rostrate apices; coste robust; strie delicate, 20 in 10 4. Zone view quadrangular. Common in fresh water. Pi. 10, Figs. 5and6. Fig. 11, Pl. 40, shows frustules containing the nuclei and chroma- tophores. DIATOMA HIEMALE (LYNG.) HEIB. Valve ovate-lanceolate to lanceolate; apices obtuse, not produced. Coste not num- erous, robust; striz moniliform. Zone view quadrate, the coste as septa deeply dividing the valve into convex elevations. Common in springs. Pl. 10, Figs. 7 and 8. In all species of Diatoma a punctum, or pore, is observed, usually at alternate ends of the two valves, by means of which a communication exists between adjoining frustules and causes them to adhere in zig-zag chains when partially separated. PLAGIOGRAMMA GREv. (1859) (plagios, on the side, and gramma, a letter) Frustules quadrangular, adnate in fascie, or free. Valve linear, elliptical, or elliptical- lanceolate, divided by two or more median and two terminal cost or with a central and two terminal hyaline spaces. Valve with two median and two terminal coste: Linear, pseudoraphe distinct .................00 2000 cee pygmeum Linear, with strie at the ends ....................... wallichianum Ovate-lanceolate cscs ceck coum ee ee eke Aleve asians obesum Valve without cost but with central and terminal nodules: PSCHA OPA DNS ADSEDE gio cic kay wesw wae eee ew eee weedeat tessellatum - THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 43 PLAGIOGRAMMA PYGM.EUM GREV. Valve linear-elliptical; pseudoraphe distinct; rows of granules transverse, usually six in each compartment, moniliform, three on each side. Blue clay. Not common. Pl. 10, Fig. 13. PLAGIOGRAMMA WALLICHIANUM GREV. Valve linear, rounded at the ends; pseudoraphe absent; transverse rows of granules, six or seven in each compartment, and two or three rows of smaller granules at each end. Blue clay. Not common. Pl. 10, Fig. 14. PLAGIOGRAMMA OBESUM GREV. Valve rhombic-lanceolate, the coste scarcely visible; pseudoraphe rather wide; rows of granules, about seven in each compartment, slightly radiating. Blue clay. Not common. Pl. 10, Fig. 12. PLAGIOGRAMMA TESSELLATUM GREV. Valve elliptical-lanceolate; central space transversely elliptical to the major axis, half the diameter of the valve; terminal spaces more or less circular or ovate. Granular mark- ings large, quadrangular, in transverse rows. Pseudoraphe not distinct. As the central space does not reach the margin, it is a question whether this form is a Plagiogramma or a new genus. Blue clay. Rare. Pl. 10, Fig. 11. OprpHora Petit (1888) (ope, an opening, and phoreo) Frustule rectangular. Valve cuneiform, linear or elliptical-lanceolate, with broad, transverse strize and a well-defined pseudoraphe or median area. The genus “‘portant des stries en forme de boutonniéres,’’ as Petit remarks, is quite near Fragilaria, under which the species here described were originally included. (See Schmidt’s Atlas, Pl. 298, where numerous forms of F. pinnata are figured.) OPEPHORA SCHWARTZII (GRUN.) PETIT Valve obovate-lanceolate or nearly linear with rounded apices; strise transverse, broad, 3 or 4 in 10 »; median area lanceolate. An inner stratum, with puncta in transverse rows, is apparent. Blue clay. Not uncommon. Variable in size. Pl. 10, Figs. 16 and 19. OPEPHORA PACIFICA (GRUN.) PETIT Valve linear, obiong, with rounded apices. Median area linear, narrow; strie punctate. Blue clay. Pl. 10, Fig. 18. Petit (Diat. Cap Horn) in his diagnosis states that the valves are cuneiform, but they are not always so. 44 THE DIATOMACEE OF PHILADELPHIA AND VICINITY _ OPEPHORA PINNATA VAR. LANCEOLATA N. VAR. Valve lanceolate; costz slightly radiate, punctate; median area broad, lanceolate. Differs from O. pinnata in outline, radiation of the cost and median area. Blue clay. Rare. Pl. 10, Fig. 17. FRAGILARIINAD Fragilaria.—Frustules in fascia. Valve with transverse striz. Pseudoraphe indistinct. Rhaphoneis.—Striz radiate; pseudoraphe distinct. Dimerogramma.—Pseudoraphe broad. Trachysphenia.—Valve cuneiform. Synedra.—Valve elongate. Asterionella.—F rustules in star-shaped clusters. FraGILARia (Lyna.) Ras. (fragilis, because of the fascie easily breaking up) Frustules rectangular, adnate in fascia, soon breaking up. Valve lanceolate, oblong or elliptical in general outline, with convex or sinuate margins; without coste; pseudoraphe narrow or indistinct; strie transverse. Chromatophores vary according to species. In some they consist of four bands on the valves; in others they are granular (Mereschkowsky). Brun divides the genus into two sections, Fragilaria proper and Staurosira. The former, with an indistinct pseudoraphe, includes the species virescens, arctica, undata and linearis, while the latter, with distinct pseudoraphe, includes capucina, harrisonii, construens and parasitica. FRAGILARIA VIRESCENS RALFS Frustules in long fascie. Valve elliptical-lanceolate, obtuse at the apices; pseudoraphe indistinct; striae, 17 in 10 u, punctate. Very common in springs and pure streams. The fascie are often a foot or more in length. Pl. 10, Figs. 20 and 21. FRAGILARIA ARCTICA GRUN. Valve oblong or elliptical, 10 » in length; strie subtle, with coarse, short strie at inter- vals on the margin and evident in zone view. Marine. Common at Cape May, N. J. Pl. 10, Figs. 22 and 23. FRAGILARIA UNDATA WM. SM. Valve in general outline linear-elliptical, with extremities produced ;striz subtle; pseudo- raphe distinct. Fresh water. Pl. 10, Figs. 24, 25, 27, 28 and 29. THE DIATOMACE OF PHILADELPHIA AND VICINITY 45 FRAGILARLA LINEALIS CSTR. Valve linear, with rounded apices; strie subtle; pseudoraphe indistinct. Marine. Cape May. Pl. 10, Fig. 37. Fig. 36 is an indeterminate form occasionally found in the blue clay. FRAGILARIA CAPUCINA VAR. MESOLEPTA RAB. Valve linear, constricted at the hyaline middle; apices slightly produced; strix, 17 in 10 up. Quite variable in size. Schuylkill River. Morrisville (Keeley). Pl. 10, Fig. 34. FRAGILARIA HARRISONII (WM. SM.) GRUN. Frustules rectangular, solitary or in twos. Valve cruciform; pseudoraphe narrow, lanceclate; striz robust, radiating in the middle, composed of confluent puncta, larger at the circumference. Blue clay. Pl. 10, Fig. 31. FRAGILARIA CONSTRUENS (EHR.) GRUN. } Valve in general outline lanceolate, with produced apices; pseudoraphe lanceolate, distinct or broad; striz subtle, 15 in 10 y. L. of valve, 10-45 yp. Staurosira construens Ehr. Odontidium tabellaria Wm. Sm. Blue clay. Pl. 10, Fig. 30. FRAGILARIA PARASITICA (WM. SM.) Frustules solitary or in twos. Valve lanceolate, sometimes constricted in the middle; pseudoraphe wide, lanceolate; strie subtle. Parasitic on other diatoms. Odontidium parasiticum Wm. Sm. Not common. Media (Palmer). In the constricted form it is known as F. construens var. binodis (Ehr.) Grun. Pl. 10, Fig. 35. An examination of the synonymy of the species of Fragilaria will convince the student of the difficulty of determining the correct name even in well-known forms. If all of the species of Fragilaria proper have granular chromatophores, and all of Staurosira are placco- chromatic, a satisfactory division can be made, but so long as these facts are not known in all species, and as authors have repeatedly confused the two divisions, the nomenclature will be uncertain. F. harrisonii is probably in any case to be separated from the others. De Toni includes it under its original name of Odontidium, which genus he places near to Diatoma. The number of species in our locality is too limited to render further discussion of any value. 46 THE DIATOMACE OF PHILADELPHIA AND VICINITY RHAPHONEIS Eur. (1844) (rhaphis, a needle) Frustule in zone view linear. Valve lanceolate or elliptical-lanceolate; pseudoraphe distinct; striz radiating, moniliform. RHAPHONEIS AMPHICEROS EHR. Valve lanceolate, broad, with apices produced; stria in curved lines, moniliform, the large granules in longitudinal lines. Blue clay. Pl. 10, Fig. 38. RHAPHONEIS AMPHICEROS VAR. RHOMBICA GRUN. Valve as in type form but shorter, with larger and mcre remote granules. Blue clay. Pl. 10, Figs. 39 and 40. RHAPHONEIS BELGICA VAR. INTERMEDIA GRUN. Valve lanceolate, rostrate; granules in longitudinal and nearly transverse, not radiating, lines. Absecon, N. J. Pl. 10, Fig. 41. DIMEROGRAMMA Ratrs (1861) (dis, two, meros, a part, gramma, a letter) Frustules quadrangular, inflated at the angles, in fascize. Valve ovate or lanceolate; strie moniliform, transverse or slightly radiate; median area or pseudoraphe broad, lanceolate. DIMEROGRAMMA MARINUM (GREG.) RALFS Valve lanceolate or linear and inflated in the middle; strie moniliform, transverse or slightly radiate; median area linear or lanceolate, sometimes not reaching the smooth ex- tremities; strie, 8in 10 y. Pl. 12, Figs. 9 and 10. Fig. 9 differs in its lanceolate outline, in having four puncta on each side in a row, and in the strize. which are radiate. DIMEROGRAMMA SURIRELLA (EHR.) GRUN. Valve elliptical-lanceolate, with rounded apices; strie moniliform, radiate; pseudo- raphe narrow, lanceolate. Blue clay. Pl. 12, Fig. 11. THE DIATOMACE.-E OF PHILADELPHIA AND VICINITY AT DIMEROGRAMMA MINUS (GREG.) RALFS Valve rhombic-lanceolate; strie- punctate, radiate; pseudoraphe lanceolate; apices smooth. Blue clay. Along the coast. Pl. 12, Figs. 12, 13, 14. TRACHYSPHENIA Petit (1877) (trachys, rough, and sphen, a wedge) Frustules rectangular. Valve cuneiform with coarse puncta in transverse and lon- gitudinal lines; pseudoraphe narrow, linear. One species only. TRACHYSPHENIA AUSTRALIS PETIT Characters of the genus. Valve small; puncta,6in 104. Allied to Dimerogramma. Shark River, N. J. Rare. Pl. 12, Fig. 15. SyNEDRA Eur. (1830) (synedrion, a sitting together) Frustules adnate in small stipitate clusters or free. Valve elongate, linear or linear- lanceolate; pseudorapke distinct; coste absent. The genus Synedra has few distinctive characters. As.Brun remarks (Diat. des Alpes et du Jura, p. 122), the dilatation of the extremities and the pseudo-nodule are of little value in classification, as the intermediate forms are so numerous. Fragilaria occurs in very long ribbons or fascize, Synedra in short fascie or radiating clusters. Fragilaria is seldom longer than three or four times the width, while Synedra is nearly always so. The former has fine, often subtle, markings and narrow pseudoraphe, while the latter has coarser punctate striz# and a more distinct pseudoraphe. Chromatophores usually consist of two bands, one on each of the valves. Karsten states that in the marine forms the chromatophores are oval or polygonal discs, each of which usually encloses a pyrenoid. SYNEDRA ULNA (NITZSCH) EHR. Frustules solitary or in twos. Valve 150-250 u in length, linear or linear-lanceolate, with rostrate apices; strie, 9 in 10 un. Common in rivers and streams. Pl. 11, Figs. 4, 7 and 11 (?). Frequently interrupted in the middle. The distinction made by Wm. Smith as to the presence or absence of the central blank space is probably not necessary, as both forms are found which are otherwise identical. Fig. 5 represents the formation of a sporangial frustule which differs from the usual form in its inflated ends prolonged into rostrate apices. Figs. 1 and 6 are sporangial frustules. 4 48 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY SYNEDRA BICEPS (KUETZ.) SCHMIDT Valve sublanceolate, inflated at the ends, apices rounded; central space not always distinct; pseudoraphe narrow; strie radiate at the ends. This is not Kuetzing’s species, if the descriptions and figures are accepted, nor is it H. L. Smith’s Type No. 545, which is 8. ulna var. danica, nor is it S. biceps Wm. Smith, but it is exactly Schmidt’s form (Atlas, Pl. 303, Figs. 10-15). Schuylkill River. PL. 11, Fig. 3. SYNEDRA DANICA KUETZ. Valve lanceolate, suddenly constricted at the rounded apices; central space frequently absent. Very common in streams. Pl. 11, Fig. 2. The figure represents an unusually large form. It differs from S. ulna only in its apices. SYNEDRA CAPITATA EHR. Valve long, linear, dilated into triangular acute apices; pseudoraphe distinct; striz radiate at the ends. Blue clay. Pl. 11, Fig. 3. SYNEDRA ACUS KUETZ. Valve very narrow, lanceolate, acicular, with obtuse apices. Common in the Schuylkill River. Pl. 11, Figs. 9 and 18. ; i SYNEDRA GOULARDI BREB. Valve constricted in the middle; apices sub-acute, sometimes slightly rostrate or capi- tate; central space evident. Neshaminy Creek (Palmer). Blue clay. Crum Creek. Pl. 11, Figs. 12 and 13. ‘i SYNEDRA PULCHELLA (RALFS) KUETZ. Valve lanceolate, taperiny to the sub-acute, rostrate or slightly capitate apices; dilated at the central hyaline space; pseudoraphe distinct. Very variable in size. Crum Creek. Schuylkill River. Rather common. Pl. 11, Figs. 14, 15, 16. SYNEDRA PULCHELLA VAR. ABNORMIS MACCHIATI ? Valve as in type form, except that one end is curved like a beak, as in 8S. hamata Win. Sm., which it resembles. Not uncommon in the Schuylkill River. Pl. 11, Fig. 17. SYNEDRA OXYRHYNCHUS VAR. UNDULATA GRUN. Valve linear-lanceolate with produced rostrate apices, asymmetrical, sigmoid; pseudoraphe narrow; pseudo-nodule large. Common in fresh water. Pl. 12, Fig. 1. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 49 SYNEDRA PULCHELLA VAR. FLEXELLA N. VAR. Frustule slightly attenuated at the ends, truncate, somewhat tumid in the middle and flexed. Valve lanceolate, with obtuse or subcapitate apices and with two almost imper- ceptible constrictions at the middle producing a tumid appearance; pseudoraphe distinct; pseudo-nodule absent. L. 56 u; strie, 14-16 in 10 x. Some valves are bent and incised on one side. The outline of the valve is that of pulchella. Common at Newtown Square. Pl. 12, Fig. 2. SYNEDRA RADIANS KUETZ, Frustules linear, in small fascie. Valve 34 u in length, linear, with apices rostrate, obtuse, sometimes slightly capitate; pseudoraphe distinct; striae about 20 in 10 p. Fresh water. Pl. 10, Figs. 32 and 33. There is difficulty in recognizing S. radians K. as described and figured by different authors. On Plate 12, Fig. 8, I have drawn a specimen from H. L. Smith’s Type Slide No. 574, labelled S. radians Kuetz., not Wm. Smith, which, however, corresponds closely to Smith’s figure (Brit. Diat. 1, P].11,Fig.89). De Toni givesS. radians Kuetz. as equivalent to 8. tenera Wm. Sm. Van Heurck’s figure of 8. radians, and also the figure of ulna var., said to be synonymous with H. L. Smith’s 8S. radians, which does not correspond to the specimens on Smith’s slide in my possession, are confusing. In Van Heurck’s Synopsis the strie are said to be 16 or 17, while De Toni describes them as subtle and from 17 to 24 in 10. The length is quite variable. Several species of Synedra resemble S. radians in the mode of growth, as they are adnate at first, in short bands, the frustules being sessile on other plants or objects, attached at the terminal nodules which, although scarcely visible in most forms, are probably pres- ent in all. The frustules are not closely connected at the free end, and soon become en- tirely detached. In Diatoma and Fragilaria, we find a punctum or pore at one end of a valve, but not in line with the pseudoraphe; in Synedra, a minute pore is usually found in the position of the terminal nodule and, in some species, indications of a central nodule are observed; the median line is wider but there is no raphe. In the fresh-water Synedre, many of which are among the longest of diatoms, living in running streams, the terminal nodules are much more indistinct, while the marine forms have distinct terminal nodules, are not, as a rule, found in bands, and assume a more naviculoid outline. SYNEDRA VAUCHERLE VAR. PARVULA (KUETZ.) RAB. Valve lanceolate, with produced or rostrate apices; pseudo-nodule wide, excentric. L. 17 p. Crum Creek. Pi. 12, Fig. 5. Fig. 6 represents a variety with coarser striex from the Schuylkill River. Both are easily mistaken for Fragilaria intermedia. 50 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY SYNEDRA FULGENS (GREV.) WM. SM. Frustules geminate or flabellate on a stipe. Valve slightly inflated in the middle and at the apices; pseudoraphe narrow; striz finely punctate, radiate at the ends. Marine. Atlantic City. Pi. 11, Fig. 10. SYNEDRA AFFINIS KUETZ. Valve lanceolate; striz marginal, leaving a broad lanceolate pseudoraphe. Common along the coast. Pl. 12, Fig. 3. SYNEDRA AFFINIS VAR. PARVA (KUETZ. ) V-. H. Valve lanceolate, slender; stria marginal, shorter than in the type. Synedra gracilis Kuetz. Common along the coast. Pl. 12, Fig. 7. SYNEDRA AFFINIS VAR. TABULATA (AG.) V. H. Valve linear-lanceolate; striz, 11 in 10 », very short. Not common. New Rochelle. Pl. 12, Fig. 4. ASTERIONELLA Hassatu( 1855) (dim. of aster, a star) Frustules linear, slightly inflated at the ends, arranged in star-shaped clusters which soon break up. Valve linear, unequally inflated at the ends. ASTERIONELLA FORMOSA HASS. Valve clavate at the ends; strie transverse, 17 in 10 », pseudoraphe very narrow or indistinct; an ovoid, hyaline area at each end. Newark, N. J. Broomall’s Lake, Media (Palmer). Pi. 12, Figs. 19, 20, 21. ASTERIONELLA INFLATA HEIB. Valve linear, capitate at each end and tumid in the middle; striz distinctly punctate; pseudoraphe indistinct, or not apparent. L. 30 u. Fresh water. May’s Landing, N. J. Pl. 12, Fig. 22. EUNOTIIN 4 Eunotia.—Frustules either free, in fascise or epiphytic. Valves arcuate. Actinella.—-Frustules, solitary or in small clusters, cuneate. Valve inflated at one end. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY sl Evnotia Expr. (1837) em. Gren. (1862) (eu, well, and noton, a back, referring to the strong, ridged dorsum) Frustules free, in fascize or epiphytic.. Valve arcuate, without costx, transversely striated; pseudoraphe absent; pseudo-nodules at each end. Chromatophores laminate along the concave zone and the valves. Very many species of Eunotia have been created to differentiate size and number of crene or undulations. An examination of certain fossil deposits of New England, as well as a gathering from the blue clay of Philadelphia, will show forms which vary infinitely. E. major and E. gracilis are scarcely distinguishable because of the intermediate variations. Fhe striz in all forms are punctate, but the puncta are frequently confluent. ANALYSIS OF SPECIES Eunotia is divided into two sections, Himantidium and Eunotia proper. In Himan- tidium, the frustules are in fascie, either short or long. Among those with short fascise are major, gracilis, and nymanniana; those with long fascie are pectinalis, solierolii and veneris. Eunotia proper includes frustules, free or epiphytic, in which the valves are not dentate on the dorsal margin, such as lunaris, hemicyclus, biceps and prerupta; and those in which the valves are dentate or crenate on the dorsum, such as monodon, triodon, diadema and others. The resemblance between Eunotia and Epithemia is noticeable. In both, the epiphytic character of the valve is seen in the shape of the frustule which is arched, and, in the free forms, is adherent at the ends only. In Epithemia, the median is more evident than the terminal nodules. In Eunotia, there is no median nodule, but the end nodules, in some species, are quite evident, and a tendency is shown to produce avery short raphe. The arrangement of puncta in valve view is similar in both genera. SEcTION 1. Him ANTIDIUM EUNOTIA MAJOR (WM. SM.) RAB. Valve arcuate, linear, subcapitate, recurved. Strie punctate, 12in10y4. L. 90-190 x. Common in fresh water. PI. 13, Figs. 1 and 2. EUNOTIA GRACILIS (EHR.) RAB. Valve with sides parallel; apices slightly capitate and revolute; strir, 10 in 104. The striz on the connective membrane more delicate than in E. major. Intermediate forms occur. Common in fresh water. Pl. 13, Fig. 3. Fig. 4 is indeterminate. EUNOTIA NYMANNIANA GRUN. Valve small, curved, with parallel dorsal and ventral margins; apices truncate and recurved into dorsal elevations; strie delicate. Blue clay. Not common. Pl. 13, Fig. 32. 52 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY EUNOTIA PECTINALIS (KUETZ.) Valve linear, arcuate, apices slightly rostrate; strie distinctly punctate with puncta in longitudinal rows nearer together at the ends. Himantidium pectinale Kuetz. Common in fresh water. Pl. 13, Figs. 6 and 7. The fascie are associated in large masses, sometimes an inch or more in diameter, and late in August are found a foot or more in length, of a beautiful chocolate color. Exceed- ingly abundant in the cedar-swamp streams of the Pine Barren regions of New Jersey. In winter, the dead frustules form a parchment-like coating upon the twigs, dead leaves, and other débris on the borders of streams. This species can scarcely be referred to Dillwyn’s Conferva pectinalis, as, in his de- scription, quoting Mueller, he says that ‘‘the filaments are of a dirty green color; seldom exceeding half an inch in length.” Dillwyn’s form is probably Fragilaria virescens, which equals Fragilaria pectinalis Ehr., while Kuetzing’s species is Fragilaria pectinalis Ralfs. It is not impossible to confuse Fragilaria virescens and Eunotia pectinalis when the zone only is seen under a low power and their mode of growth is similar. , EUNOTIA PECTINALIS VAR. UNDULATA RALFS Valve as in type form, but with undulate margins. Common in the cedar swamps of New Jersey. Pi. 13, Figs. 8 and 10. EUNOTIA PECTINALIS VAR. SOLIEROLII (KUETZ.) Valve as in type, but with internal divisions as though in the process of reduplication. Not common. Moorestown, N. J. (Palmer). Pl. 13, Fig. 9. - EUNOTIA PECTINALIS VAR. VENTRICOSA GRUN. As in type, but with the valves tumid in the middle. May’s Landing, N. J. Pi. 13, Fig. 12. Fig. 11 is a form found in the blue clay. It differs in the coarser puncta from the var. ventricosa. In outline it resembles Eunotia arcus Wm. Sm., which is Ceratoneis arcus (Ebr.) Kuetz., but the central nodule is not present as in the latter form, which connects Eunotia and Cymbella. It may be a form of FE. luna Ehr. (A. S., Atlas, Pl. 286, Figs. 33 and 34.) EUNOTIA VENERIS KUETZ. Valve with convex dorsal and straight ventral margins, more or less constricted near the sub-acute apices. Strie subtle, punctate. Eunotia incisa Greg. May’s Landing, N. J. Blue clay, Pavonia, N. J. Pl. 13, Figs. 30 and 31. THE DIATOMACE-E OF PHILADELPHIA AND VICINITY 53 EUNOTIA (PROPER) EUNOTLA LUNARIS (EHR.) GRUN. Frustules sessile, solitary or in clusters. Valve arcuate, narrow, attenuated toward the apices, which are sometimes slightly rostrate or rostrate-capitate; transverse strix, 14 in 10 p, punctate. Very common in ditches, especially in the spring. Variable in length. Pl. 12, Figs. 24 and 25. EUNOTIA HEMICYCLUS (EHR.) RALFS Valve semicircular, with obtuse apices; strim transverse, punctate; terminal nodules minute and indistinct. Hammonton Pond, N. J. Rare. Pl. 12, Fig. 23. The genus Pseudo-Eunotia was created by Grunow for forms like Eunotia, but with- out terminal nodules. As, however, in E. lunaris and E. hemicyclus nodules are evident, although not so large as in many species, I include these two forms as heretofore under Eunotia. EUNOTIA BICEPS EHR. Valve linear, slightly arcuate, narrow, with rounded apices somewhat revolute; striae, 16 in 10 p. ’ : May’s Landing, N. J. Pl. 13, Fig. 27. EUNOTIA PRERUPTA EHR. Valve convex on dorsal side, apices dilated and truncate; strie distant at centre. Common in the blue clay. Pl. 13, Fig. 5. EUNOTIA PR-ERUPTA VAR. BIDENS GRUN. Valve with two undulations; otherwise as in type. Eunotia bigibba Greg. With the type. PI. 13, Fig. 19. EUNOTIA ROBUSTA RALFS Valve arcuate, with several or numerous dorsal ridges or crene which decrease in rela- tive size in proportion to their number. Striz radiate, variable in distance apart, and in size of puncta. Ralfs included under this one name the following species named by Ehrenberg: FE. diodon (2 crenz); E. triodon (3); E. tetraodon (4); E. pentodon (5); E. diadema (6); E. heptodon (7); E. octodon (8); E. enneadon (9); E. decadon (10); E. hendecadon (11); E. duodecadon (12); E. serra (13); E. prioritis (14); all more than 20, E. polyodon. E. scalaris,with from 15 to 17 crene, and E. icosodon with 20, may be added. It is probable that all of these forms occur at May’s Landing, N. J. The forms with more than eight crene are comparatively rare. In the blue clay those with from four to six are most common. Pl. 13, Figs. 13, 14, 15, 16, 17, 21, 24, 25. 54 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY EUNOTIA BACTRIANA EHR. Valve linear, apices revolute, acute, dentate on the dorsal margin, with one acute crena near each end. Tom’s River, N. J. Rare. Pl. 13, Fig. 18. EUNOTIA BIDENTULA WM. SM. Valve with straight ventral margin, and with twe undulations on the dorsum; apices large, rounded. May’s Landing, N. J. Rare. Pl. 13, Fig. 20 (not Schumann’s form, which has angular crenz). EUNOTIA FORMICA EHR. VAR. ? Valve turgid in the middle and at the apices wiich are unilaterally truncate. Pensauken, N. J. (artesian well). Pl. 13, Fig. 26 (not a typical form). The following are forms which appear to be indeterminate, or, in any case, are scarcely worthy of distinction by specifie names, as might be said of others of the innumerable variations of this genus: Fig. 23, Pl. 13, probably a form of prerupta. Newtown Square. Fig. 28, Pl. 13, from the blue clay. Fig. 29, Pl. 13, an asymmetrical form, apparently abnormal, but not rare at May’s Landing, N. J. Fig. 17, Pl. 38. Valve convex on the dorsal side, incised on the ventral; strize about 15 in 10 yp, closer at the ends; L. 30 ». Schuylkill River. Fig. 18, Pl. 38. Valve arcuate, asymmetrical, broader at one end; terminal nodules large; strie, 10 in 104; L. 474. Gloucester, N. J., artesian well. Numerous variations of the above species are illustrated in Schmidt (Atlas, Pls. 285-291). ACTINELLA Lewis (1865) (dim. of actin, a ray) Frustules solitary, or in small clusters, -sub-cuneate or nearly linear. Valve arcuate, rounded at one end and suddenly widened at the other into a cup-shaped or lychnoid inflation. ACTINELLA PUNCTATA LEWIS Valve with fine, transverse striz; on the margin, puncta at intervals; terminal nodules distinct. May’s Landing, N. J. Pl. 12, Figs. 16, 17, 18. Fig. 17, from Tom’s River, N. J., is an approach toward A. brasiliensis Grun. Fig. 18 represents the frustules geminate, a frequent occurrence. THE DIATOMACE OF PHILADELPHIA AND VICINITY 55 NAVICULOIDE.E In discussing the Naviculoid group, the general divisions of Cleve are here followed, and all diatoms having a true raphe are included. I have added the genus Epithemia and also Rhopalodia, partly because they contain a raphe of a certain kind and partly because they resemble the markings of certain of the genus Hantzschia in the following group, although in other respects there is probably no similarity. — The difficulty of combining the numerous genera into groups which are naturally affiliated is avoided in the following arrangement based on superficial similarities, and is intended merely as an artificial key. To unite all forms having a raphe and which are symmetrical with valves similar and not sigmoid, under the one genus Navicula, as has been the custom previous to the publication of Cleve’s monograph, would result in associating species differing in so many respects in relation to structure of the valve and cell contents that it seems advisable to retain the new genera, especially as the original genus is likely to be still further reduced when more is known of the structure and life history of the group. KEY TO THE GENERA Valves dissimilar. Achnanthee symmetrical .3..4.37 aag ciao sere koi ee Covconeis asymmetrical to the longitudinal axis...................0020--2 eee ee Anorthoneis to the transverse axis .........2 22... e cece eee eee ee eee Rhoicosphenia ii ONO IEW cok secu ed beeeasneere are ksd ap emeeen ues Achnanthes Valves similar. and asymmetrical asymmetrical to the longitudinal axis Valves parallel 305.5500. eee witch oun ee eee eae Cymbella valves not: parallel isco: sc cuccnaica boas niababiecetece bare oan deiars Amphora valves keeled, twisted (sometimes symmetrical).......... Amphiprora valves keeled 2 scar eee eeua rene eee Seis Tropidoneis valves reniferm and keeled ................-220 0000005 Auricula median line sigmoid at the ends.........0..¢+sase0eese. Scoliotropis asymmetrical to the transverse axis strie punctate and costate...... Mahe teseeiiocen dh tek denis Gomphoneis Strim-punctate cg. ceca sce tes heise wees ee See Gomphonema Valves similar, symmetrical and sigmoid strie oblique......... Dyas Apher a baw e eee eee Pleurosigma strie at right angles .............. 00. cece cee eee ee Gyrosigma Valves similar, symmetricai, not sigmoid strie punctate, nodules elongated..............-.-.-+-+ -Frustulia strie subtly punctate, centra! nodule forked ............ Amphipleura strie punctate and reticulate, in two strata.........--.- Dictyoneis strim punctate and alveolate, in three strata............ Trachyneis striae punctate, In two stratas:.:cce05s.0rdeee ne eens Brébissonia strie interrupted by blank lines. 2.06 ....02seexaee9 es Anomecconeis 56 THE DIATOMACE OF PHILADELPHIA AND VICINITY strie crossed by longitudinal lines..................... Caloneis striae oblique, median fissures in opposite directions ....... Neidium strice punctate and costate, median line with horns........ Diploneis strie punctate; valves separated by septate plates ........ Mastogloia strie punctate, central area dilated into astauros......... Stauroneis strie punctate, area without stauros or horns ........... Navicula strie costate, not punctate ................ 2c eee eee Pinnularia ACHNANTHEZ Frustules stipitate, free Or parasitic. Valves cuneate, elliptical or suborbicular, dis- similar, bent along the transverse or the longitudinal axes, the lower valve with a true raphe and central and terminal nodules, the upper valve with a pseudoraphe or median line. Rhoicosphenia.—Stipitate; valves with transverse puncta, bent along the transverse axis, cuneate, with diaphragms at the ends. Anorthoheis.—Free; puncta radiate; valves bent slightly along the transverse axis, suborbicular. Cocconeis:—Parasitic; valves elliptical, usually bent along the longitudinal axis; stricz punctate, transverse and longitudinal. Achnanthes.—Stipitate; valves lanceolate or elliptical, bent along the transverse axis; striz transverse, punctate; costz sometimes present. | RHOICOSPHENIA GRUN, (1860) (rhoicos, curved, and sphen, a wedge) Frustule in zone view curved; valves cuneate, dissimilar, the upper with a pseudoraphe, the lower with a raphe. Chromatophore a single plate along both valves, and one of the inner walls of the zone. Conjugation as in Gomphonema, with which it is generally associated in classification. RHOICOSPHENIA CURVATA (KUETZ.) GRUN. Valve clavate, with rounded apex and base; lower valve with raphe, a narrow axial area and slightly radiate, punctate strie; the upper valve with a narrow pseudoraphe and parallel striz; a short diaphragm at the ends of each valve. Length usually from 15 to 25 p, but frequently of twice the size. Common in Crum Creek. Pl. 19, Figs. 25, 26, 27. ANORTHONEIS GRUN. (1868) (anorthos, not straight) Valves dissimilar, the upper valve with an excentric axial area, the lower with an excentric raphe. ANORTHONEIS EXCENTRICA (DONK.) GRUN. * Valves orbicular, with radiating, punctate striz, closer at the circumference, produc- ing the appearance of a border. Axial area not reaching the ends. Frustules occur free on the sands of the sea-shore. L. 25 to 50 pn. Belmar, N. J. Pl. 16, Figs. 30 and 31. THE DIATOMACE-E OF PHILADELPHIA AND VICINITY 57 COCCONEIS EHR. (1835) em. GRUN. (1368) (coccos, a berry) Valves elliptical, dissimilar, the upper valve with a pseudoraphe and the lower with a genuine raphe and nodules, usually with a rim or annulus. Frustules epiphytic. Cocconeis is generally considered as a degenerated form of Mastogloia, as indicated by the “‘obsoletely loculiferous rim.’’ The frustules are usually bent along the longitudinal axis, probably because of the attachment to the curved stems of water-plants. The cell contents of ouly a few species are known. In C. pediculus, a single chromato- phore occurs on the inside of the upper valve. In conjugation, two cells open and secrete a gelatinous mass from which an auxospore is formed. , Cleve separates the forms having a loculiferous rim (Cocconeis) from those without a rim (Eucocconeis). As the rim is easily detachable, the distinction is often made with difficulty. COCCONEIS SCUTELLUM EHR. Valves elliptical, the upper with a linear or lanceolate pseudoraphe and coarse puncta in transverse and radiating lines; the lower valve with much finer puncta in radiating lines, a lanceolate axial area and, sometimes, a loculiferous rim. Along the coast. Common, but extremely variable. Pl. 16, Fig. 21 (upper valve). Fig. 18, var. ? COCCONEIS SCUTELLUM VAR. ORNATA GRUN. Upper valve with linear axial area, and transverse and radiating punctate lines which end at the border in a double row of finer puncta; lower valve with much finer puncta, a lanceolate axial area and a loculiferous rim. Atlantic City. Common. Pl. 16, Figs. 27 and 28. The forms along the coast vary infinitely both in size and appearance. The var. ornats is very abundant along the entire coast. In any gathering, valves are found with or without the rim which is frequently seen detached. The upper valve is sometimes with- out the double row of puncta. Fig. 21 represents an upper valve more coarsely punctate than usually occurs. Very many intermediate forms might be noticed. COCCONEIS PEDICULUS EHR. Valves rhombic-elliptical, very convex, somewhat asymmetrical; the upper valve with a linear pseudoraphe, sometimes widened near the ends, and slightly radiating, finely punc- tate strie; lower valve with narrow, axial area and finely punctate, radiating stric. Not uncommon in fresh water. Abundant in a ditch at Paoli, Pa. Pl. 16, Figs. 23 and 24. COCCONEIS PLACENTULA EHR. Valve elliptical; upper valve with a linear or lanceolate axial area, and punctate strisze in transverse and radiating rows, the puncta at equal distances; the lower valve with a lanceolate axial area, radiating rows of puncta, and a wide border of finely punctate, radiating strie, separated from the central part of the valve by a narrow hyaline zone. Common in salt, brackish and fresh water. Pl. 16, Figs. 19 and 20. 58 THE DIATOMACE-E OF PHILADELPHIA AND VICINITY COCCONEIS PLACENTULA VAR. LINEATA (EHR.) V. H. As in the type, except that the upper valve has the puncta arranged in zig-zag, giving the appearance of sinuous, longitudinal lines. _* Common along the coast. Pl. 16, Fig. 29. C. pediculus and C. placentula are the only species I have found in fresh water. Cleve states that the former occurs also in brackish wate. The following are among the species placed by Cleve in a new genus, Eucocconeis, distinguished by the absence of a loculiferous rim. COCCONEIS DIRUPTA GREG. Valves elliptical, the lower with fine puncta in slightly radiating lines, 4 narrow axial area and a central area dilated into a lanceolate, stauriform space; the terminal fissures turned in opposite directions; the upper valve similar to the lower valve except in the ab- sence of raphe and nodules. Along the coast. New Rochelle. Pl. 16, Fig. 22 (lower valve). - COCCONEIS PELLUCIDA GRUN. Valves elliptical, the upper with broad axial area, on each side of which are fine, lon- gitudinal rows of short strie; the lower valve with more numerous longitudinal rows, a mar- ginal line and indistinct raphe; the terminai fissures small and turned in opposite directions. New Rochelle. Pl. 16, Figs. 25 and 26. In the var. minor Grun. the median line of the lower valve is sometimes slightly sigmoid. ACHNANTHES BORY (1822) (achne, froth or down, and anthos, a flower) Frustules stipitate, solitary or in short fascic, flexed. Valves elliptical or lanceolate, naviculoid, dissimilar, the lower with a raphe and median and terminal nodules, and the upper with a pseudoraphe or median space. The genus has no apparent affinity with any other. ACHNANTHES LONGIPES AG. Valves linear-elliptical, obtuse at the apex, sometimes slightly constricted in the middle. Connective zone with transverse, subtly punctate strie, interrupted by longitudinal lines. Central nodule of lower valve dilated into a stauros reaching the margin. Valves costate, the cost alternating with double rows of fine puncta. Along the coast, in estuaries. Pl. 16, Figs. 1 and 2. A. longipes is the only species in our locality considered by Cleve as belonging te the genus; the other forms, distinguished by the absence of costs, are included in the genus Achnanthidium of Kuetzing. In A. longipes, the chromatophores consist of scattered, rounded granules, while in Achnanthidium the chromatophore is a single plate along the upper valve, or a double one THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 59 along the connective zone. It is necessary, therefore, to distinguish between A. longipes and the following group, but, because of the long continued union of all of the stipitate forms having the general appearance of a true Achnanthes, I shall continue to describe the local species under the generally accepted name. ACHNANTHES BREVIPES AG. Valves without costx; striz moniliform; upper valve with excentric pseudoraphe or median line; otherwise as in A. longipes. Along the coast, in estuaries. Pl. 16, Fig. 3. ACHNANTHES SUBSESSILIS KUETZ. Valves linear-elliptical, rounded at the ends; upper valve with excentric pseudoraphe; striz moniliform, puncta smaller than in A. brevipes. Along the coast, in estuaries. Pl. 16, Figs. 4, 5, 6. The three species described above are named from the length of the stipe, but this varies considerably and is not of special significance. ACHNANTHES INFLATA (KUETZ.) GRUN. Valves more or less inflated in the middle, usually with the stauros of the lower valve asymmetrical and wider than in A. subsessilis, with which it agrees in size and markings. Gloucester, N. J. (artesian well). Pl. 16, Figs. 7 and 8. ACHNANTHES COARCTATA (BREB.) GRUN. Valves lanceolate, oblong, broad at the ends and constricted in the middle. Stauros wide; pseudoraphe of the upper valve excentric; striz slightly radiate on the lower valve; puncta small. Blue clay. Pl. 16, Fig. 9. ACHNANTHES LANCEOLATA (BREB.) GRUN. Valves more or less elliptical; stria radiating, 12 in 10 », punctate; on the lower valve a horse-shoe shaped hyaline space on one side of the centre; on the upper valve an irregular stauros, not reaching the margin. L. 8-20 un. In springs. Abundant at Newtown Square. Pl. 16, Figs. 10, 11, 12. ACHNANTHES EXIGUA GRUN. Valves oblong-lanceolate, with rostrate ends, sometimes slightly constricted in the middle. Stauros rather wide; strie punctate, radiating, 22in 104. L. 10-12 p. Stauroneis exilis Kuetz. (not Achnanthes exilis Kuetz). Frequently found in aquaria where I have kept it growing continuously for years. Pl. 16, Figs. 14 and 15. ACHNANTHES LINEARIS FORMA CURTA H. L. SMITH Frustules solitary or geminate. Valves linear-elliptical, or elliptical-lanceolate. Lower valve without distinct axial area; upper valve with axial area widencd in the middle; strie slightly radiate (?). L.7. One of the smallest of diatoms. 60 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY This form I found in a pure gathering covering the sides of a greenhouse tank at Elm; N. J. It was sent to Prof. H. L. Smith, who determined it as forma curta of A. linearis. Pl. 16, Figs. 16 and 17. ACHNANTHES DANICA (FLOEGEL) GRUN. Valves rhombic-lanceolate, with subacute ends. Strix, 25 in 10 y, radiate. Lower valve with stauros widened toward the margin, and cleft into three divisions. fo Pavonia, N. J. (artesian well). Pl. 16, Fig. 13. I have seen the lower valve only. Cleve states that the upper valve is costate with “alternating fine lineole twice as close as the costz.”’ CYMBELLA AG. (1830) (cymbe, a boat) Frustules free, stipitate or enclosed in tubes. Valve boat-shaped; median line asym- metrical, straight or curved. Chromatophore single, covering the entire interior of the frustule, except the ventral part of the zone and the median lines. Its longitudinal axis is on the dorsal part of the zone. A pyrenoid lies in a fold of the chromatophore on the dorsal part. The genus includes the former genera of Cocconema, characterized by stipitate forms, and Encyonema in which the frustules are frequently enclosed in gelatinous tubes. SecTION 1.—CyMBELLA FROPER. FRUSTULES FREE OR SOMETIMES STIPITATE CYMBELLA HETEROPLEURA (EHR.) KUETZ. Valve nearly symmetrical, lanceolate, with rostrate, produced apices; median line neatly straight; axial area linear, widened in the middle; stria radiate, punctate. Blue clay. Pl. 18, Fig. 10. CYMBELLA CUSPIDATA KUETZ. Valve broad, elliptical, with rosirate, somewhat acute, apices and nearly straight, ven- tral margin; median line straight, axial area linear, widened in the middle; striz radiate, punctate. Blue clay. Pl. 18, Fig. 17. CYMBELLA NAVICULIFORMIS AUERSWALD Valve linear-elliptical, with abruptly produced apices; ventral margin straight; median line almost straight; axial area narrow, central area large, rounded; strie distant in the middle, closer at the ends. Fresh water. Pl. 18, Fig. 6. CYMBELLA EHRENBERGII KUETZ. Valve lanceolate, with ventral margin nearly straight and apices sub-rostrate; median line straight, excentric; axial area narrow; central area widened in the middle; striae coarsely punctate. ° Fresh water. Pl. 18, Fig. 9. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 61 CYMBELLA AFFINIS XUETZ. Valve about three times as long as broad, strongly convex on the dorsal side and straight on the ventral; apices sub-rostrate; striae punctate; axial area narrow, not widened in the middle; median line curved; a small or indistinct punctum on the ventral side of the median line (not shown in the figure). Common in ponds. Abundant in East Park Reservoir. Pl. 18, Fig. 18. TS CYMBELLA EXCISA (KUETZ.) DE TONI Valve as in affinis, but with tumid and excised ventral margin; a punctum is found on the ventral side (not shown in the figure). According to Cleve this is a variety of C. affinis. Common in ponds. Pl. 18, Figs. 15, 19 ? CYMBELLA PARVA (WM. SM.) CL. Valve semi-lanceolate, with produced apices; ventral margin slightly | ; axial area narrow; striz coarsely but obscurely punctate. C. affinis and C. parva are quite variable, the latter differing by its laieedlate form and the absence of a punctum, which, however, is sometimes difficult to recognize. Ina gathering of C. parva, it is quite possible to find numerous abnormal forms which appear to be sporangial, so that specific distinctions are difficult if based on occasional specimens. Common in ponds. Pl. 38, Fig. 14. CYMBELLA AMPHICEPHALA N-EGELI Valve unequally elliptical, with broad, rostrate apices; axial area narrow; median line straight; central area small, rounded; stria, 12 in 10 » on the dorsal, closer on the ventral, side and at the ends. Kirkwood Pond, N. J. Pl. 18, Fig. 16. CYMBELLA SINUATA GREG. Valve linear-elliptical, gibbous on the ventral side; axial area indistinct; central area widened on the ventral side nearly to the margin. Crum Creek. Pl. 18, Fig. 13. Section 2.—CoccoNEMA. FRUSTULES STIPITATE CYMBELLA ASPERA (EHR.) CL. Valve large, cymbiform, arcuate on the dorsal, slightly gibbous on the ventral side; axial area linear, broad, slightly widened in the middle; no row of puncta on the ventral side. The puncta form curved longitudinal lines and the innermost row on the ventral side appears sometimes distant from the others, but not as in C. cistula. Cocconema asperum Ehr. Cymbella gastroides Kuetz. 62 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY Not Cymbella gastroides H. L. Smith, Type No. 118, which is C. mexicana A. S., having a punctum in the middle of the central nodule; in outline it is like C. gastroides var. minor Kuetz. Blue clay. Pl. 18, Fig. 1 (an unusual form, but it resembles Grunow’s. (Diat. Franz Jos. Land, Pl. 1, Fig. 7.) CYMBELLA CYMBIFORMIS (KUETZ.) BREB. Valve cymbiform, slightly gibbous on the ventral margin; apices broad, somewhat truncate; a punctum occurs on the ventral side of the median line; strie, 8 in 10», closeiy punctate. Kirkwood Pond, N. J. Pi. 18, Fig. 2. CYMBELLA CISTULA (HEMPR.) KIRCHN. Valve cymbiform, with gibbous ventral margin and truncate apices; a distinct row of several puncta occurs below the median line in typical forms. Blue clay. Pl. 18, Fig. 3. ’ CYMBELLA LANCEOLATA (EHR.) KIRCHN. Valve cymbiform, with gibbous ventral margin; apices truncate; axial area very nar- row, scarcely widened in the middle; stria with fine close puncta. Kirkwood Pond, N. J. Pl. 18, Fig. 4. CYMBELLA MEXICANA (EHR.) A. 8. Valve broad, with gibbous ventral margin and sub-rostrate, truncate apices; median line with reflexed terminal fissures; strie with coarse puncta; a large punctum occurs in the centre of the central area. Blue clay. Pl. 18, Fig. 5. CYMBELLA TUMIDA (BREB.) V. H. Valve cymbiform, with gibbous ventral margin and abruptly rostrate ends; median line arcuate; axial area narrow; central area large, orbicular; below the central nodule is a punctum; striz punctate. Crum Creek. Pl. 18, Fig. 7. SEcTION 3.—ENCYONEMA. FRUSTULES IN TUBES CYMBELLA VENTRICOSA KUETZ. Valve lunate, with straight or slightly gibbous ventral margin; axial area indistinct; median line straight or nearly so; strie punctate. Very common, but extremely variable. The ventral margin is sometimes straight and sometimes quite gibbous. Pl. 18, Figs. 14, 22; Pl. 38, Fig. 16; Pl. 40, Fig. 8. THE DIATOMACE_E OF PHILADELPHIA AND VICINITY 63 C. ventricosa is considered by some authors to be equivalent to C. affinis var. semi- circularis Lagerst., Encyonema prostratum (Berk.) Ralfs, E. exspitosum Kuetz. and E. auerswaldii Rab. H. L. Smith’s Type Slide of C. ventricosa Ag. is said to equal C. affinis Kuetz., but the specimens appear to me to be equivalent to C. ventricosa Kuetz. Cleve unites many forms, including E. cespitosum, under C. ventricosa. CYMBELLA PROSTRATA (BERK.) CL. Valve semi-elliptical, obtuse at the apices, which are sometimes prolonged and turned downwards; median line straight, terminal nodules distant from the ends; axial area nar- row, central area rounded; strie in radiating, slightly curved lines, indistinctly punctate. Common in fresh water; occasional in brackish. Pl. 18, Fig. 21 (represents a frequent variation). CYMBELLA PHILADELPHICA N. SP. Valve semi-elliptical-lanceolate, with rounded apices; ventral margin strongly gibbous; terminal nodules distant from the ends; axial area broad, central area widened on the dor- sal side; strice radiate, not curved nor of unequal length, indistinctly punctate, 10 in 10 on the dorsal, 8.in 10 » on the ventral side. L. 86 u. This form approaches Encyonema prostratum (Berk.) Ralfs, Schmidt’s Atlas, Pl. 71, Fig. 7, but differs in the strize and the axial and central areas. Blue clay of Philadelphia. Rare. Pl. 18, Fig. 8. CYMBELLA TRIANGULUM (EHR.) CL. Valve semi-elliptical, with acute ends; median line straight; ventral side half the width of the dorsal, with straight, slightly convex or concave margin; strim radiate, coarsely punctate. Gleonema triangulum Ehr. Baker’s Run, Willistown, Pa. Pl. 18, Fig. 24. CYMBELLA TURGIDA (GREG.) CL. Valve semi-elliptical, with acute ends; ventral margin gibbous; ventral side half the width of the dorsal; median line straight; terminal fissures turned downwards; axial area broad; strie radiate, coarsely punctate. Baker’s Run, Willistown, Pa. Pl. 18, Fig. 23. CYMBELLA TURGIDA (GREG.) CL. VAR. ? Valve lunate, with gibbous ventral margin; median line straight; terminal fissures turned downwards near the ends; axial area lanceolate, striz radiate on the dorsal side, 8 in 10, punctate, 9 on the ventral side, closer at the ends where they are convergent. L. 65h. Not a typical form. Willistown, Pa. Pl. 18, Fig. 12. ; ee CYMBELLA RHOMBOIDEA N. SP. ac Valve rhomboidal, with acute ends; dorsal part one and a half times the width of the ventral; median line nearly straight, with terminal fissures turned downwards near the ends; axial area broad, not widened in the middle, except slightly on the ventral side; striz 5 64 THE DIATOMACE4 OF PHILADELPHIA AND VICINITY radiate, distant in the middle of the dorsal side where they are 7 in 10», coarsely punctate, the puncta in longitudinal lines, 9 in 10 » on the ventral side, closer at the ends. L. 69 u. Baker’s Run, Willistown, Pa. Pl. 18, Fig. 11. CYMBELLA GRACILIS (RAB.) CL. Valve semi-lanceolate, with acute ends; median line nearly straight, with terminal fissures turned downwards, distant from the ends; axial area linear; ventral margin straight or slightly gibbous in the middle. Hammonton Pond, N. J. Pl. 18, Fig. 20. CYMBELLA LACUSTRIS (AG.) CL. Valve elliptical-lanceolate, with obtuse ends, nearly symmetrical; median line straight, terminal fissures distant from the ends; strie radiate in the middle, convergent at the ends, coarsely lineate. Belmar, N. J. Pl. 18. Fig. 25. va AMPHORA EHR. (1840) (amphora, a jar) Valves asymmetrical along the longitudinal axis, as in Cymbella, but with the plane passing through the dorsal and ventral sides of one valve at an angle with that of the other. As Cleve states, Cymbella and Amphora are forms of Navicula ‘‘with both valves similar and asymmetrical along the longitudinal axis,’”’ and the difference between Cymbella and Amphora is in the “degree of asymmetry.” If, following H. L. Smith’s diagrams (Lens, Vol. 2, 1873, p. 66), we assume that the usual form of the valve in Navicula is elliptical or lan- ceolate, and the zone view is rectangular, we have in Cymbella an arcuate median line and a more or less reniform valve, while the zone view remains rectangular with the valves parallel. Now, if the valves are asymmetrical along the longitudinal axis, and one side of ove valve is separated from the corresponding side of the opposite valve by a wider connec- tive zone than is the case on the other side, the transverse section of the frustule will appear cuneate, as in Amphora, and the connective zone will be wider on one side than the other. When, therefore, we examine an entire frustule as it is usually seen, we shall find the two raphes of the valves in focus at the same time on the ventral side, and, by changing the focus, the convex sides of the same valves are seen, the dorsal view with, usually, a wider connective zone. As an illustration, compare Figs. 5 and 6, on Plate 15, Fig. 6 being the ventral, and Fig. 5 the dorsal view. As Amphore are epiphytic or parasitic, they are considered, as Cleve remarks, like Achnanthes and Cocconeis, as ‘‘degenerated forms.” Chromatophores usually single, lying on the ventral connective zone. Mereschkowsky describes nine forms. Cleve divides the genus into a number of groups as follows: Amphora proper.—Connective zone not complex; valves with longitudinal lines on the dorsal side; coarsely punctate or costate. Diplamphora.—Zone complex; otherwise as in Amphora. Halamphora.—Longitudinal lines absent; frustule elongate, with protracted ends. THE DIATOMACEE OF PHILADELPHIA AND VICINITY 65 Oxyamphora.—Zone complex; longitudinal lines absent; frustule elliptical; valve lunate, with or without a central stauros; strie punctate. Amblyamphora.—Zone complex; frustule rectangular; valve lunate; strie punctate; axial and central areas indistinct. Psammamphora.—Zone not complex; frustule rectangular; central nodule frequently dilated to a stauros; no axial or central area. Cymbamphora.—Valve semi-lanceolate; median line straight, approximate to the ven- tral margin. AMPHORA AMPHORA ROBUSTA GREG. Frustule elliptical, truncate; valve lunate, with straight ventral margin; median line biarcuate; ventral side with coarse, radiate striz, 6 in 10 yu, on both sides of the median line. Along the coast. Pl. 15, Fig. 1. AMPHORA PROTEUS GREG. Frustule elliptical, truncate; valve lunate, with straight ventral margin; median line biarcuate; no central area. Strie on the dorsal side not interrupted, 9 in 10 4. Ventral side striate toward the ends. Differs from A. robusta chiefly in size and coarseness of puncta. Extremely variable in size. Common along the coast. Pl. 15, Figs. 5, 6, and 19. AMPHORA OVALIS (BREB.) KUETZ. Frustule elliptical, truncate; valve lunate; median line biarcuate; striz on dorsal side 10-16 in 10 u. Var. libyca (Ehr.) Cl.—Central area distinct on the dorsal side. Var. pediculus (Kuetz.) Cl.—Central area and nodule quite distinct. Strix finer than in var. libya. Common in ponds. Quite variable. Pl. 15, Fig. 7. AMPHORA GIGANTEA VAR. FUSCA A. S. Frustule elliptical; valve lunate, with straight ventral margin. Axial area absent on the dorsal side; dorsal striz, 10 in 10 », punctate. Ventral part hyaline except at the ends, which are obliquely striated, with short, punctate lines. L. 70-120 yz. Absecon, N. J. Pl. 38, Fig. 1. DIPLAMPHORA AMPHORA CRASSA GREG. Valve linear-elliptical, with obtuse, incurv rved ends. Median line biarcuate. Axial and central areas indistinct on the dorsal side; striz coarsely punctate, interrupted by a longi- tudinal line on the dorsal side. Along the coast. Pl. 15, Fig. 3. 66 THE DIATOMACE OF PHILADELPHIA AND VICINITY AMPHORA AREOLATA GRUN. Valve with straight ventral margin; median line straight, approximate to the ventral margin; axial area indistinct; severa] longitudinal lines crossed by apparent costz which alternate with rows of fine puncta. Blue clay. Rare. Pl. 15, Fig. 11. HALAMPHORA AMPHORA COFFIFORMIS (AG.) KUETZ. Frustule lanceolate, truncate; zone with numerous divisions. Valve arcuate on the dorsal and nearly straight on the ventral side; ends protracted or slightly capitate. A. aponina Kuetz. A. salina Wm. Sm. Along the coast. Pl. 15, Figs. 8 and 18. OxYAMPHORA AMPHORA LINEOLATA EHR. Frustule membranaceous, elliptical, truncate, with broad ends. Zone with numerous divisions. Dorsal part striated transversely; ventral side with longitudinal lines. A. plicata Greg. A. hyalina H. L. Smith, Type No. 64. Along the coast. — Pl. 15, Figs. 9 and 10. AMPHORA OSTREARIA BREB. Frustule oblong, with rounded angles. Zone with five or more divisions transversely striated. Central area narrow, biarcuate; central nodule dilated to a stauros. Valve nar- row, with arcuate dorsal and straight ventral margin, acute at the ends. Strie transverse, finely punctate. A. vitrea Cl.; A. porcellus Kitton; A. quadrata Bréb.; A. elegans Greg. Appearance varies according to the position of the valve. Along the coast. Pl. 15, Figs. 12 and 21. AMPHORA LEVIS GREG. Frustule oblong, hyaline and membranaceous. Valve linear or slightly arcuate, with ventral margin tumid in the middle; ends obtuse; central nodule dilated to a stauros; median line very narrow, biarcuate, coinciding with the dorsal margin at the ends; strie transverse, punctate. Blue clay. PI. 15, Fig. 18. AMPHORA ACUTA GREG. Valve lunate, with acute ends; ventral margin straight; ventral side very narrow. Central nodule dilated to a stauros; strie transverse, punctate. Along the coast. Pl. 15, Fig. 20. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 60 AMBLYAMPHORA AMPHORA OBTUSA GREG. Frustule rectangular. Valve linear, obliquely rounded at the ends, with arcuate dor- sal, and straight ventral, margin; median line biarcuate; strie, 18-20 in 10 u. Along the coast. Common. Pl. 15, Fig. 4. PsaMMAMPHORA AMPHORA ARENARIA DONK. Frustule hyaline, rectangular, slightly tumid in the middle, with rounded angles. Valve linear with broad ventral side and straight or sinuate ventral margin. Stricw, 24-27 in 10 » (Cleve). Common along the coast. PI. 15, Fig. 17. The distinction between A. obtusa and A. arenaria is not always evident if the valves alone are seen. The former has a complex zone, the latter a simple zone, and the valve has finer strie. Cleve’s descriptions and references in regard to these two forms do not agree with the descriptions and figures of H. L. Smith, or with the figures of Schmidt. The valves of most Amphore are capable of assuming various outlines according to their position. AMPHORA OCELLATA VAR. CINGULATA CLEVE Frustule rectangular. Valve linear, with dorsal margin arcuate and the ventral margin straight. Central nodule with a stauros on the dorsal side. Squan River, N. J. Pl. 15, Figs. 14 and 15. CYMBAMPHORA AMPHORA ANGUSTA VAR. EULENSTEINII GRUN. Valve lanceolate, acute at the ends. Median line straight, approximate to the margin. Axial area widened on the dorsal side, indistinct on the ventral; striae punctate. A. eulensteinii A. S. . Common along the coast. Pl. 15, Fig. 16. On Pl. 40, Figs. 21, 22, and 23, I have attempted, imitating H. L. Smith’s figures (Lens, l.c.), to illustrate the difference in the transverse sections of Navicula, Cymbella and Amphora. Fig. 21 represents the transverse section of a convex Navicula, in which the valves ecg and fdh are parallel, and the median nodules ¢ and d are central. Fig. 22 is a transverse section of Cymbella in which the valves are nearly parallel and the median nodules are excentric. The girdles on one side, ea and af, are narrower than gb and bh on the other side. Fig. 23 is a transverse section of an Amphora in which the valves appear in zone view with the median nodules of both valves on the same side. The girdles on the ventral side, ea and af, are narrower than gb and bh on the dorsal side. The girdles on the dorsal side are seldom as broad as gb and bh, the valve extending over a great part of the dorsal side to g’ and h’. 68 THE DIATOMACE OF PHILADELPHIA AND VICINITY AMPHIPRORA EHR. (1843) (amphi, on both ends, and prora, a prow) Frustule twisted in the longitudinal axis, constricted in the middle; zone complex, with numerous divisions crossed by fine strie. Valve lanceolate, acute. The raphe con- fined within a sigmoid keel or extension of the valve; the central and terminal nodules indistinct. Strie transverse, punctate, with coarser stri# at the junction of the keel and lower part of the valve. Chromatophores single, with indented border except in A. pulchra, in which there are two chromatophores with entire borders. AMPHIPRORA ALATA KUETZ. Frustule with a row of puncta at the junction line. Valve linear, acute at the ends. Median line sigmoid. Stris lineate on the lower part of the valve, punctate on the keel. Along the coast. Not common. Pi. 14, Fig. 3. AMPHIPRORA PULCHRA BAIL. Frustule with sigmoid connective zone. Valve very convex, with sinuate keel and junction lines evident. In-zone view and in valve view, one half of the frustule, owing to the elevation of the keel, is wider than the other half. Strix punctate, coarser on the keel. Not uncommon along the coast. Pl. 14, Figs. 1 and 2. AMPHIPRORA CONSPICUA GREV. Valve linear or elliptical, with acute ends. Median line sigmoid, but the junction lines not evident. Striz lineate, with coarser lines near the middle. Not common. Port Penn, Delaware River. Pl. 14, Fig. 4. AMPHIPRORA ORNATA BAIL. Frustule membranaceous, constricted in the middle, with well-marked folds extending from the junction line in both directions. Valve lanceolate, constricted in the middle and with protracted ends. Keel undulate on the edge. A beautiful, transparent and delicate form, the only fresh-water species in our locality. Delaware Water Gap, Pa. Pl. 14, Figs. 6 and 7. AMPHIPRORA PALUDOSA WM. SM. Frustule membranaceous, constricted, with truncate ends. Valve linear, with acute ends. Strix scarcely visible. Cape May (Cleve). Pl. 14, Fig. 5. TROPIDONEIS CLEVE (1891) (tropis, a keel) Frustule oblong, constricted in the middle; keel not sigmoid. Axial area not evident. Striz very fine, punctate, in longitudinal lines. THE DIATOMACE OF PHILADELPHIA AND VICINITY 69 TROPIDONEIS LEPIDOPTERA (GREG.) CLEVE Valve with straight, median excentric line. Keel unilateral, projecting above the median line in zone view; central area small. Transverse strie finely punctate. As usually seen, the valve is inclined. According to Karsten there are two chromatophores on the connective zone, each divided into four parts, each of which contains a large oval pyrenoid. Amphiprora lepidoptera Greg. Along the coast. Pl. 14, Figs. 8 and 9. AURICULA CASTRACANE (1873) (auricula, the ear, the shape of the valve) Frustule globose. Valve reniform or cymbiform, elevated into a keel which is not sigmoid. Median line biarcuate. Differs from Amphiprora in not having a sigmoid keel. AURICULA MUCRONATA (H. L. SMITH) PERAGALLO In zone view, the median line deeply bisects the longitudinal axis, ending in a mucro- nate central nodule. Connective zone complex. Valve very complex, with ventral margin nearly straight and raphe excentric. Central nodule near the margin, terminal nodules small. Striz, 35-40 in 10 » (Cleve). Chromatophore single, on the ventral part. Amphora mucronata H. L. Smith. Amphora (?) insecta Grun. Auricula insecta (Grun.) Cleve. ‘‘A rare and very curious pelagic species” (Peragallo, Diat. Villefranche). Prof. H. L. Smith included this form in his first century of “Species Typice Diatom- acearum,” which was issued prior to 1876, the date of publication, in Schmidt’s Atlas, of Amphora insecta Grun. Atlantic City, N. J. Rare. Pl. 15, Fig. 2. SCOLIOTROPIS CLEVE (1894) _ (scolios, twisted, and tropis, a keel) Frustule linear, oblong. Median line sigmoid near the ends. Valve with transverse coste alternating with two intermediate rows of puncta in oblique lines. SCOLIOTROPIS LATESTRIATA VAR. AMPHORA CLEVE Valve asymmetrical, with the median line curved. Frustule sub-acute at the ends. Median lines not on the same side of each valve of the frustule. Abundant at Cape May, N. J. Not common elsewhere. Pl. 14, Figs. 10 and 11. GOMPHONEIS CLEVE (1894) (gomphos, a peg, and neis (naus)) Valve elongated, asymmetrical to the transverse axis; axial area narrow; central area rounded, stigmatic; striz radiating, cost alternating with double rows of fine puncta. An indistinct, longitudinal line near the border. Chromatophores and conjugation have not been determined. 70 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY GOMPHONEIS HERCULANEUM (EHR.) CL. Valve clavate, with rounded apex; costz, 13 in 10 y, alternating with double rows of fine puncta, 22 in 10 y, in oblique rows; axial area narrow, central area rounded, with one stigma. Gomphonema capitatum Ehr. var. herculaneum Ehr., H. L. 8., Type Slide No. 177. Common in the blue.clay. Pl. 19, Fig. 2. Pl. 38, Fig. 15, zone view of young frustuie. GOMPHONEIS MAMILLA (EHR.) CL. Valve lanceolate, with rounded apex and base; strie costate, 10 in 10 u, alternating with double rows of fine puncta; axial area linear, sometimes oblique, central area small, with one or more stigmas. Blue clay. Rare. Pl. 19, Fig. 1. In one frustule I noticed one valve with one stigma and the other with four stigmas. The difference between G. mamilla and G. elegans is not very great. In the latter the central area is larger and the longitudinal lines not so near to the margin. The stigmas form a circlet. There appears to be a coincidence in the relation of Gomphoneis to Gom- phonema, and that of the true Achnanthes to the group described by Cleve under Achnan- thidium. In Gomphoneis and Achnanthes the striation is both costate and punctate while in Gomphonema and Achnanthidium the striation is punctate only. GOMPHONEMA AG. (1524) (gomphos, a peg, and nema, a filament) Valve elongated, asymmetrical with respect te the transverse axis; stria transverse, usually radiate, punctate. ; Chrematophore band single, the middle lying on one zone. In conjugation, according tc Thwaites and Pfitzer, from two mother cells, which do not form a positive union, two auxospores are developed parallel to the original frustules. In Plate 19, Fig. 19, I have drawn a representation of the auxospore formation as I have frequently observed it in a gathering sent me by Mr. T. C. Palmer, containing G. angus- tatum, a common species in this locality. The sagittal plane of the valve of the auxospore is at right angles to the plane of the valve of the mother cel!. Two valves of one of the mother cells are seen separated, one on each side of the auxospore which is nearly twice the length of the original frustules. The two valves of the other mother cell are not shown as they are not usually found closely united. In the figure one valve alone of the auxo- spore is seen, the opposite valve not being in focus. The valves of the auxospore are usually more or less arcuate, as in Cymbella, to which the genus is closely allied. Grunow divides Gomphonema into two groups, Asymmetrice and Symmetrice, according to the presence or absence of stigmas. Cleve suggests Stigmatice and Astigma- tice as more suitable in order to agree with the Cymbellex. The Stigmatice are found chiefly in fresh water, sometimes in brackish. All of the marine forms belong to the Astig- matice, which, however, include some common fresh-water forms. Many species of Gomphonema are stipitate, some occur in gelatinous masses, and others are free. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 71 GOMPHONEMA MONTANUM SCHUM. Valve slightly biconstricted, with obtuse apex and basis, somewhat cuneate; axial area linear, widened in the middle unilaterally; stigma, one; strie about 11 in 10 », more distant in the middle, punctate. Gomphonema subclaratum var. montana (Schum.) Cl. Pavonia, N. J., artesian well. Rare. Pl. 19, Fig. 3. GOMPHONEMA GEMINATUM LYNG. Valve biconstricted, with large, rounded, sub-truncate apex and broad, sub-truncate basis; striz, 9 in 10 yu, radiate in the middle, alternately longer and shorter, transverse at the basis and near the apex where they again radiate, coarsely punctate, puncta, 12 in 10 z. Axial area linear; central area rounded, with several large stigmas in a longitudinal row; terminal fissures hook-shaped. Blue clay. Pl. 19, Fig. 4. GOMPHONEMA LANCEOLATUM VAR. INSIGNIS (GREG.) CL. Valve lanceolate; axial area narrow; central area unilateral with one stigma; stri«e with coarse and distant puncta. Common and variable. Gomphonema insigne Greg. Pl. 19, Figs. 6 and 12. Fig. 12 shows a unilateral central area. Fig. 6 is more clavate in outline with small central area. In both forms the coarse puncta are in distinct longitudinal lines in the. middle. GOMPHONEMA ACUMINATUM VAR. TURRIS (EHR.) CL.? Valve clavate, with cuneate, acute apex; axial area distinct; central area unilateral with one stigma. Blue clay. Pl. 19, Fig. 11. GOMPHONEMA ACUMINATUM VAR. TURRIS (EHR.) CL. Valve clavate, with cuneate apiculate apex and narrow basis; axial area narrow, with a unilateral central space; stigma opposite the short strie; stria more radiate in the upper part, distant in the middle. Smith’s Island, Delaware River. Pl. 19, Fig. 5. GOMPHONEMA ACUMINATUM VAR. CORONATA (EHR.) CL. Valve twice constricted, with broad, cuneate apex; strie radiate in the middle, conver- gent near the apex and radiate at the apex. Variable in size and outline. Blue clay. Fresh water. Common. Pl. 19, Fig. 7. GOMPHONEMA ACUMINATUM VAR. TRIGONOCEPHALA (EHR.) CL. Valve broad, with cuneate apex; axial area narrow; central area unilateral with one stigma. Pavonia, N. J., artesian well. Pl. 19, Fig. 20. 72 THE DIATOMACE OF PHILADELPHIA AND VICINITY GOMPHONEMA CONSTRICTUM EHR. Valve clavate, constricted beneath the abruptly rounded apex, gibbous in the middle, strie alternately longer and shorter; axial area narrow, central area unilateral, with one stigma. Common in fresh water. Pl. 19, Fig. 8. GOMPHONEMA SPH/EROPHORUM EHR. Valve clavate, with capitate or rostrate-capitate apex and narrow basis; axial area very narrow; central area small, unilateral, with one stigma. Common in fresh water. Pl. 19, Figs. 9 and 10. Fig. 10 appears to be a transitional form having a more distinct axial area and rostrate apex. GOMPHONEMA AUGUR EHR. Valve broadly clavate, truncate and apiculate at the apex; basis sub-acute; axial area distinct; central area small, unilateral with one stigma; strie with distant puncta. Blue clay. Willistown, Pa. Pl. 19, Fig. 21. GOMPHONEMA INTRICATUM KUETZ. Valve narrow, lanceolate, slightly gibbous in the middle; axial area distinct; central area transverse with one stigma; strie parallel. Quite variable. Common in fresh water. Pl. 19, Fig. 14. GOMPHONEMA ANGUSTATUM KUETZ. Valve lanceolate, with sub-rostrate apex and basis; axial area indistinct; central area unilateral, with one small stigma; strie slightly radiate, indistinctly punctate. Very common in fresh water. Pl. 19, Figs. 18 and 19. : Fig. 19, as stated above, represents the formation of an auxospore. GOMPHONEMA ZQUALE GREG. Valve linear-lanceolate, nearly symmetrical, with capitate apex and basis; axial area narrow; central area unilateral, with one stigma; strie radiate in the middle, slightly con- vergent at the ends. Gomphonema intricatum var. equale (Greg.) Cl. Blue clay. Not common. Pl. 19, Fig. 15. GOMPHONEMA SARCOPHAGUS GREG. Valve linear, irregular in outline, with rounded apex and basis; axial area distinct; central area small, unilateral, with one stigma; striz irregular with coarse, distinct puncta. Occasional in fresh water. Pl. 19, Fig. 16. GOMPHONEMA CAPITATUM EHR. Valve clavate, broad at the sub-truncate apex and slightly constricted, or with paral- lel margins; axial area linear, central area stellate, with one stigma; striz in the middle alternately longer and shorter. Blue clay. Pl. 19, Fig. 22. THE DIATOMAUCEE OF PHILADELPHIA AND VICINITY 73 GOMPHONEMA PARVULUM VAR. MICROPUS (KUETzZ.) CL. Valve clavate, with rounded apex and basis; axial area indistinct; central area unilateral, with a small stigma; strie distant in the middle. Common. Pl. 19, Fig. 17. GOMPHONEMA VENTRICOSUM GREG. Valve clavate, with broad apex and produced, rounded basis; axial area narrow, widened in the middle; stigma one; strie distant in the middle, finely punctate. Blue clay. Pl. 19, Fig. 13. GOMPHONEMA OLIVACEUM LYNG. Valve clavate, with broad apex and narrow basis; axial area very narrow; central area irregular, without stigma; striz radiate, finely punctate. Very common. Pl. 19, Fig. 23. GOMPHONEMA BRASILIENSE VAR. DEMERARS GRUN.? Valve lanceolate, with sub-cuneate apex and narrowed basis; axial area lanceolate, broad; no stigma; median fissures remote; strie parallel, 12 in 10 up, punctate, the puncta obsolescent, small or interrupted. Willistown, Pa. Rare. Pl. 19, Fig. 24. PLEUROSIGMA WM. SM. (1852) (pleura, a side, and sigma, the letter s) Valve lanceolate, sigmoid; axial area very narrow, central area small; strix punctate, in transverse and oblique lines. Cleve divides the forms usually known as Pleurosigma into two genera, Pleurosigma and Gyrosigma. Pleurosigma includes all forms having oblique rows of puncta, while Gyrosigma includes all having longitudinal rows. Both have transverse strie. The former consists entirely of marine species, while in the latter the species are found in fresh, brack- ish and salt water. The endochrome in Pleurosigma, according to Mueller, consists of two bands which differ in the median part of each valve. Mereschkowsky says that the endochrome is so divided as to form four bands, two on each valve, that their position is different in different species, and that they are not the same on valves of the same frustule. Cleve prefers to classify the species of Pleurosigma and Gyrosigma in accordance with the outline of the valve and the flexure of the median line. I shall, however, retain the method used by Peragallo and Grunow and arrange the forms according to the striation. (1) Osuique Srri# aBouT 90 Decrees, More Distivct THAN THE TRANSVERSE PLEUROSIGMA FORMOSUM WM. SM. Valve elongated, slender, gently sigmoid, acute at the ends; oblique striz crossing each other at about 90 degrees; 10-16 in 10 yu; transverse striz, 14-20 in 10 yu (Cleve). Along the coast. Pl. 22, Fig. 5. 74 THE DIATOMACE OF PHILADELPHIA AND VICINITY PLEUROSIGMA OBSCURUM WM. SM. Valve linear, not sigmoid, or scarcely so; ends obtuse, subconical; raphe sigmoid, near the margin at the extremities; transverse and oblique strize equidistant, 28 in 10 » (Wm. Sm.). Abundant at Greenwich Point, Philadelphia. Pl. 22, Fig. 4. (2) OBLIQuE Stri# Cioser At THE ENps PLEUROSIGMA NAVICULACEUM BREB. Valve lanceolate, slightly sigmoid at the extremities; raphe strongly sigmoid near the margin at the ends; central nodule large, rounded; oblique striz, 13-14 in the middle, closer at the ends; transverse striz, 18-20 in 10 u (Peragallo). Long Island Sound. PI. 22, Fig. 6. PLEUROSIGMA VIRGINIACUM H. L. SMITH Valve slightly sigmoid, with acute ends; raphe more sigmoid than the valve, excen- tric near the ends; oblique striz,in different directions at the centre, 13 in 10 y, closer and less distinct at the ends; central nodule small but prominent because of its thickness, producing by diffraction an apparently wide area (somewhat exaggerated in the figure). L. 95 yp, usually larger. P. affine var. fossilis Grun. (Peragallo). P. normanii var. fossilis Grun. (Cleve). Common in the blue clay. Pl. 22, Fig. 8. (3) OstiquE StTRi# 60 DEGREES PLEUROSIGMA ANGULATUM (QUEKETT) CL. Valve rhomboidal, with sub-rostrate or produced ends; central nodule rhomboidal; raphe central; transverse and oblique strie at an angle of 60 degrees, equidistant, 18-22 in 10 pz. Navicula angulata Quekett. Along the coast. Pl. 22, Fig. 3. PLEUROSIGMA STRIGOSUM WM. SM. Valve lanceolate, with sub-acute, somewhat revolute, apices; oblique stria at an angle of about 60 degrees, otherwise as in angulatum. Along the coast. Not common. Pl. 22, Fig. 1. PLEUROSIGMA ZSTUARII BREB. Valve lanceolate, with produced apices; raphe less sigmoid than the valve and excen- tric; oblique striz, 19-21 in 10 yu, at an angle of about 60 degrees. Along the coast. Common. Fl, 22, Fig: 7. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY a1 uo (4) OstrqvE StRL£ 60 DEGREES, THE TRANSVERSE More Distant PLEUROSIGMA RIGIDUM WM. SM. Valve nearly straight or slightly sigmoid, with obtuse ends; raphe central, excentric near the ends; oblique striw, 17-21, transverse, 16-19 in 10 uw. (Peragallo). New Rochelle, N. Y. Pl. 22, Fig. 2 (very near the var. gigantea Grun.) GYROSIGMA HASSALL (1845) (gyros, curved, and sigma) Valve lanceolate, sigmoid; axial area very narrow, central area small; strive punctate, in transverse and longitudinal rows. Chromatophores two, in long and narrow bands, perforated, differing from those of Pleurosigma. The elzoplasts are also arranged differently in the two genera. (Méresch- kowsky, Etudes sur l’Endochrome des Diatomées, Imperial Academy of Petrograd, 1901, Vol. 11, No. 6, p. 18 et seq.) The arrangement is according to Peragallo. (1) Lone:tupinaL Strr# More Distant THan THE TRANSVERSE GYROSIGMA HIPPOCAMPUS (EHR.) Valve lanceolate, sigmoid, with obtuse ends; raphe nearly central; transverse striae 15-17, longitudinal, 10-12 in 10 z. Navicula hippocampus Ehr. Pleurosigma hippocampus (Ehr.) Wm. Sm. Gyrosigma attenuatum (Kuetz.) Cl. Long Island Sound. Pl. 23, Fig. 3. (2) LoNGITUDINAL AND TRANSVERSE STRL® NEARLY Equa GYROSIGMA BALTICUM (EHR.) CL. Valve with margins parallel nearly to the extremities, which are suddenly unilaterally sub-conical and obtuse; raphe sigmoid; transverse and longitudinal strie nearly equally distant, 15 in 10 » (Per.). L. 200-360 uz. Navicula baltica Ehr. Pleurosigma balticum (Ehr.) Wm. Sm. Common along the coast. Pil, 23, Fig. 2. GYROSIGMA PARKERI VAR. STAURONEIOIDES GRUN. Valve lanceolate, slightly sigmoid, ends produced into beaks with sub-acute apices; raphe straight in the middle part; central nodule elliptical; transverse strie, 21, and longitu- dinal, 24 in 10 » (Per.). An apparent stauros, variable in width, extends to the margin and, in consequence, the median transverse stri are more evident. L. 75 p. Schuylkil! River. Rather rare. Pl. 23, Fig. 7. 76 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY GYROSIGMA SIMILE (GRUN.) Valve slightly sigmoid, broad, with obtuse ends; raphe sigmoid, nearly central; trans- verse striz, 15, longitudinal, 16-17 in 10 p (Per.). Pleurosigma simile Grun. Gyrosigma balticum var. similis (Grun.) Cl. Shark River, N. J. Pl. 23, Fig. 4. (3) TRANSVERSE Stri® More Distant GYROSIGMA ACUMINATUM (KUETZ.) CL. Valve sigmoid, tapering to the sub-acute ends; raphe central; transverse and longi- tudinal stria nearly equally distant, 17 or 18 in 10 uw (Per.). Frustulia acuminata Kuetz. Port Penn, Delaware River. Pi. 23, Fig. 5. * GYROSIGMA STRIGILIS (WM. SM.) CL. Valve sigmoid, with obtuse ends; raphe doubly sigmoid; axial area rather wide; trans- verse striz, 13, and longitudinal, about 16 in 10 p. Long Island Sound. Not common. Pl. 23, Fig. 1. GYROSIGMA KUETZINGII (GRUN.) CL. Valve sigmoid, lanceolate, with sub-acute ends; raphe central, the central nodule elliptical; transverse strie, 21-23, and longitudinal, 25-26 in 10 pz. Pleurosigma spencerit var. acutiuscula Grun. Pleurosigma spencerii var. kuetzingit Grun. Common in fresh water. Pl. 38, Fig. 12. GYROSIGMA SCALPROIDES (RAB.) CL. Valve slightly sigmoid, with obtuse ends; raphe nearly straight; central nodule ellip- tical; transverse striz, 22, slightl- radiate and more distant in the middle; longitudinal strix, 29in 104. L. 60 u. Common in streams. Pl. 38. Fig. 9. In Pl. 23, Fig. 6 represents a form more sigmoid. GYROSIGMA SPENCERIIL VAR. NODIFERA GRUN. Valve sigmoid, with obtuse ends; raphe central; central nodule obliquely elongated; transverse strize, 17-18 in 10 », curved in the middle of the valve, longitudinal striz, 22 in JO yp. L. 150 pz. Blue clay. Pl. 23, Fig. 8. GYROSIGMA PROLONGATUM (WM. SM.) CL. —_ Valve narrow, lanceolate, produced into beaks, curved in a contrary direction; raphe central; transverse striz, 20-21 in 10 y, longitudinal closer. L. 140 p. Along the coast, northward. Pl. 38, Fig. 13. I have not seen any specimens south of New England, but they will probably occur. THE DIATOMACE-E OF PHILADELPHIA AND VICINITY 77 (4) Srriz ALIKE, ExTrRemITIES Proptcep GYROSIGMA FASCIOLA (EHR.) CL. Valve lanceolate, attenuated into curved beaks turned in opposite directions; raphe central, straight, except at the beaks; transverse strix, 22, longitudinal, 24 in 10 u (Per.). New York Bay. Pl. 23, Fig. 9. FRUSTULIA AG. (1824); em. GRUN. (i865) (frustulum, a small piece) Valves naviculoid, similar, usually free but sometimes enclosed in gelatinous tubes or embedded in mucus. Median line between two thickened ribs. Central and terminal nodules frequently elongated. Surface of valve with fine puncta in longitudinal and trans- verse lines appearing hyaline under medium powers. Chromatophores, two, extending along the girdle. They differ from those of Navicula in being separated from the wall in the middle by a hemispherical mass of protoplasm. According to Pfitzer, each chromatophore is divided in the middle, allowing a connection between the hemispherical mass and the central plasma mass. Schmitz states that the chromatophore is thickened in the middle and contains a pyrenoid. In conjugation, two frustules form two cylindrical bodies which later become conical and from which are formed the sporangial valves twice the usual size. FRUSTULIA LEWISIANA (GREV.) DE TONI Valve elliptical or linear, with rounded ends; terminal nodules elongated, at a distance from the ends; strize, 24 in 10 pz. Port Penn, Delaware River. Along the coast. Pl. 17, Fig. 1. FRUSTULIA RHOMBOIDES (EHR.) DE TONI Valve lanceolate or rhombic-lanceolate, rounded at the ends; central and terminal nodules short; striz, 206 in 10 », sometimes coarser. Common in fresh water. Pl. 17, Fig. 2. FRUSTULIA RHOMBOIDES VAR. AMPHIPLEUROIDES GRUN. Valve rhombic-lanceolate; central and terminal nodules elongated; median line some- what excentric. Blue clay. Pl. 17, Fig. 3. FRUSTULIA RHOMBOIDES VAR. SAXONICA (RAB.) DE TONI Valve smaller than in rhomboides, with somewhat produced ends, closer median ribs and rounded central nodule. Fresh water. Pi. 17, Fig. 6. FRUSTULIA VULGARIS (THWAITES) DE TONI Valve elliptical-lanceolate, with rounded or sometimes sub-rostrate ends; central and terminal nodules slightly elongated; striz delicate, closer at the ends. Frustules at first in gelatinous tubes. Colletonema vulgaris Thwaites. Fresh water. Pl. 17, Fig. 4. 78 THE DIATOMACE OF PHILADELPHIA AND VICINITY FRUSTULIA INTERPOSITA (LEWIS) DE TONI Valve linear-elliptical, rounded at the ends; terminal nodules short. Navicula interposita Lewis. Along the coast. Port Penn, Delaware River. Pl. 17, Fig. 5. AMPHIPLEURA KUETZ. (1844) (amphi, on both sides, pleura, a side) Frustules free, in gelatinous masses or in tubes. Valve linear-lanceolate; central nodule narrow, extending half the length of the valve or more, then forking toward the ends. Terminal nodules prolonged, as in Frustulia, into a ‘‘porte-crayon-shaped’’ figure. Chromatophores two, very short. AMPHIPLEURA PELLUCIDA KUETZ. Frustules free or in mucous masses. Valve fusiform; forks about one-fourth the length of the valve; strie transverse, punctate, 36-40 in 10 » (J. J. Woodward). Occasional in the Delaware River. Pl. 17, Fig. 9. AMPHIPLEURA RUTILANS (TRENTEPOHL) CL. Frustules enclosed in gelatinous tubes. Valve linear-lanceolate, obtuse at the ends; forks about one-third the length of the valve; striz, 28 in 10 u. Corferva rutilans Trentepohl. Schizonema dillwynit Wm. Sm. Abundant at Belmar, N. J. Pl. 17, Fig. 10. Fig. 11 represents a portion of the gelatinous tube containing frustules. DICTYONEIS CLEVE (1890) (dictyon, a net) Frustules oblong. Valve lanceolate, constricted in the middle (in our species); an outer layer finely punctate and an inner layer of reticulations; the margin of the valve divided into large, quadrate cells. The genus Dictyoneis includes species at one time ascribed to Mastogloia and Navic- ula. The structure, however, is not like that of either, as the loculi are attached to the valve and are not separable as in Mastogloia, and the cell-wall is not like that of any Navicula. , Cleve remarks that Dictyoneis is found in warm waters. Lewis found one specimen at Black Rock Harbor, L. I., and one in the Delaware River blue clay. The specimens here described I found living on the New Jersey coast. DICTYONEIS MARGINATA VAR. TYPICA CLEVE Valve panduriform, with cuneate lobes; axial area narrow, linear, scarcely, or not at all, widened in the middle; terminal fissures in contrary directions; outer stratum finely punctate, about 25 in 10 y, in parallel strie; inner stratum coarsely reticulated. Four and one-fourth times longer than broad; marginal cells, 5 in 10 », smaller or obsolescent in the middle of the valve; cells of the valve in irregular transverse rows, 10-12 in 10 y. L. 95 u. Navicula marginata Lewis. Absecon, N. J. Pl. 20, Fig. 3. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 79 DICTYONEIS MARGINATA VAR. COMMUTATA CLEVE Valve four and one-half times longer than broad; cells of the valve in irregular, trans- verse rows about 11 in 10 y; marginal cells nearly equal, 6 in 104. L. 125 u. Absecon, N. J. ; Pl. 20, Fig. 2. DICTYONEIS MARGINATA VAR. MAXIMA N. VAR. Valve with cuneate segments; marginal cells, 4in 10 u; cells of the valve, 5 in 10 pz, obsolescent in the middle and smaller; transverse strix, 25 in 10 yp. Atlantic Coast. Rare. Pl. 20, Fig. 1 (from a specimen found at Colon). TRACHYNEIS CLEVE (1894) (trachys, rough, and neis (naus), named from the chief species) Valve more or less linear or linear-lanceolate. It appears to be composed of three strata, one an interior, coarsely dotted, an exterior of fine puncta in longitudinal striae, scarcely visible, and a median of transverse anastomosing coste forming irregular alveoli. Chromatophores, two or four bands on the zone (Mereschkowsky). TRACHYNEIS ASPERA VAR. INTERMEDIA GRUN. Valve linear-elliptic; axial area a stauros widened outward and unilateral. Strice of the median layer of radiating rows of oblong alveoli. Along the coast. Not common. PI. 17, Fig. 15. The type form and its numerous varieties are quite ubiquitous. Very large specimens occur in the Antarctic regions, especially in material from Ross Island, S. Victoria Land (Shackleton Ant. Exp.). BREBISSONIA GRUN. (1860) (named after Alphonse de Brébisson, the distinguished French naturalist) Frustules stipitate; valve lanceolate; stri# transverse in the middle, radiate at the ends. Median area narrow, central nodule elongated, terminal fissures at a distance from the ends. Valve with an outer finely punctate stratum. At one end of one valve in each frustule is found a conspicuous punctum, the plas.-a pore of Otto Mueller, thrcugh which the frustule is connected with the gelatinous stipe, analogous to the pore in Diatoma connecting the zig-zag frustules. Chromatophore single, lying on one girdle and passing over to each valve. BREBISSONIA BCECKII (KUETZ.) GRUN. Valve lanceolate, with sub-acute apices; strie, 3-4 in 10 yu, not reaching the median line. ‘ Blue clay. Very rare. Common in brackish water at Chestertown, Md. (T. C. Palmer.) Pl. 17, Fig: 7: 6 80 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY BREBISSONIA PALMERII, N. SP. Valve rhombic-lanceolate, with cuneate ends and produced apices. Central nodule more elongate and terminal fissures further from the ends than in B. boeckii. Pavonia, N. J. (artesian well, depth of 40 ft.). Rare. Pl. 17, Fig. 8. I take pleasure in naming this species after Mr. T. Chalkley Palmer, of Media, Pa., the author of numerous papers on the Diatomacee. Lewis partly describes a similar form, which he does not name, as a species of Navicula found in the blue clay at Kaighn’s Point, N. J. (Lewis, “‘New and Intermedi- ate Forms,” etc., p. 15, Pl. 1, Fig. 8.) ANOMCONEIS PFITZER (1871) (anomoios, unlike, and neis (naus), a boat) Valve lanceolate, axial area narrow, central area widened; transverse strize punctate, the puncta in longitudiral rows or interrupted by blank lines. A single chromatophore lies along one of the girdle sides and extends over the valves, each of the two parts beirg deeply notched or slit at the ends. According to Schmitz there are two pyrenoids, but Heinzerling thinks there is but one. Cleve considers this genus not well founded, as it is based upon the cell contents of but one species, the structure of the other species not being known. As the forms here de- scribed are easily recognized by the interrupted puncta, the genus is, at least, convenient. ANOMCEONEIS SPHZROPHORA (KUETZ.) CL. Valve elliptic-lanceolate, ends rostrate-capitate. Axial area narrow, central area rounded, larger on one side of the median line than the other. Strie very slightly radiate, 16 in 10 p, punctate, the puncta interrupted by longitudinal blank lines. Pfitzer states that the central plasma mass is unequal on the two sides. Navicula spherophora Kuetz. Fresh and brackish water. Not common. Pl. 40, Fig. 2. @e ANOMCEONEIS SERIANS (BREB.) CL. Valve lanceolate, acute; axial area lanceolate; striz, 24 in 10 u; puncta elongate. Not common in this locality, but abundant northwards; fossil in the peat deposits of New England. May’s Landing, N. J. = Pl. 17, Fig. 12. Forma minor—Valve rhombic-lanceolate, smaller than the type. May’s Landing, N. J. Pl. 17, Fig. 13. ANOMCEONEIS FOLLIS (EHR.) CL. Valve rhomboid, tumid in the middle and obtuse at the produced ends. Central area lanceolate; striz radiate in the middle, transverse at the ends. Navicula follis Ebr. Navicula trochus Kuetz. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 81 Reported by Lewis as very rare in the blue clay of the Delaware River. I have not seen it in this locality. The figure is drawn from a specimen in the W. Bridgewater, Mass., deposit. Pl. 17, Fig. 14. CALONEIS CLEVE (1894) (calos, beautiful) Valve convex, linear or lanceolate in general outline, with transverse, smooth or finely punctate striz crossed by one or more longitudinal lines. Endochrome of two chromatophores lying one on each valve, entire in some species and deeply cleft in others. CALONEIS LIBER (WM. 8M.) CL. Valve linear, with parallel margins and rounded ends; axial area narrow, central area orbicular; striz transverse in the middle, slightly divergent at the ends, 16 in 10 u; terminal fissures slightly curved in the same direction; longitudinal line median. L. 82 u. Atlantic coast, chiefly southward. PI. 40, Fig. 1. CALONEIS SILICULA (EHR.) CL. Valve linear, gibbous in the middle, with broad sub-cuneate ends; axial area narrow, central area rounded; longitudinal line marginal; strie parallel or nearly so, 16 to 18 in 10 y. Navicula silicula Ehr. Navicula limosa Donk. Blue clay. Pl. 21, Fig. 3 (var. genuina Cl.). CALONEIS SILICULA VAR. INFLATA (GRUN.) CL. Valve gibbous in the middle, with rounded ends; central area elliptical. Schuylkill River. Pl. 21, Fig. 4. C. silicula may be recognized by its yellow color when dry. Its varieties are extremely numerous. CALONEIS TRINODIS (LEWIS) Valve divided into three segments of equal width; ends cuneate and usually produced; axial area elliptical with a lunate marking on each side; strie radiate in the middle, else- where parallel, about 20 in 10 u, finely punctate; longitudinal line marginal, scarcely visible; the strize become fainter toward the axial area. Occasional in streams and in the blue clay. Abundant in a water-trough at Ash- bourne, Pa. oe ; Pl. 21, Fig. 8. 5 = ae I have retained Lewis’ name as specific. Lewis, wrongly, I think, ascribes his species to Navicula trinodis Wm. Sm., which is not figured by Smith, but is illustrated by Van Heurck (Syn. Pl. 14, Fig. 31a), and is named by Cleve Navicula contenta var. biceps Arnott. 82 THE DIATOMACEE OF PHILADELPHIA AND VICINITY De Toni includes Lewis’ name under Rhoiconeis trinodis (Wm. Sm.) Grun. Rhoiconeis is achnanthiform, with frustules arcuate, and the species is named by Cleve Achnanthes trinodis (Arnott). Calonetis schumanniana (Grun.) Cl., to which as a variety Cleve unites Lewis’ form, appears to resemble it only in the lunate marks. Fig. 9 represents a single specimen found in the Pavonia deposit and which IJ believe to be an abnormal form of C. trinodis, differing only in the degree of inflation and in the larger central area. Navicula trinodis var. inflata Schultze, from Staten Island, is the same form figured by Lewis, who states that certain specimens have produced apices. CALONEIS PERMAGNA (BAIL.) cL. Valve lanceolate, with produced apices; median line nearly straight; axial area lanceo- late, irregular or slightly unilateral, about half the width of the valve; striz, 9 in 10 y, radi- ate and indistinctly punctate; longitudinal lines double. L. 100-200 yu. Pinnularia permagna Bail. Common in brackish water. Pi. 21, Fig. 1. CALONEIS PERMAGNA VAR. LEWISIANA N. VAR. Valve lanceolate, with undulating sides and sub-cuneate apices; axial area less than one-third the width of the valve; striz radiate, 12 in 10 yn, indistinctly punctate; longitudi- nal lines double, closer together than in the type. L. 140 u. Lewis illustrates this variety in ‘New and Rare Species,” Pl. 2, Fig. 11, and states that it is probably Navicula esox Kuetzing. This is an error, as Kuetzing’s species is Pin- nularia esox Ehr., a form near P. major. Rather common in the Delaware River. Pl. 21, Fig. 2. CALONEIS FORMOSA (GREG.) CL. Valve lanceolate, with sub-cuneate apices; axial area one-fourth to one-fifth the width of the valve, somewhat unilateral, dilated in the middle; striz, 12-14 in 10 y, radiate, punc- tate; longitudinal lines double, distinct. Variable in size and outline. Abundant along the shores of the Delaware River. Pl. 21, Fig. 18. CALONEIS BREVIS VAR. VEXANS (GRUN.) CL. Valve elliptical-lanceolate; apices obtuse; median fissures distant; axial area narrow; central area large, orbicular; longitudinal lines close together, median. Shark River, N. J. Pl. 21, Fig. 5. CALONEIS WARDII CL. Valve linear, ends cuneate; axial area linear; central area dilated to a stauros reaching the margin; striz parallel, radiate at the ends, 18 in 10 u; longitudinal lines marginal. Not uncommon in the Delaware River. Pl. 21, Figs. 6 and 7. THE DIATOMACE.X OF PHILADELPHIA AND VICINITY 83 CALONEIS POWELLII (LEWIS) CL. Valve linear, with cuneate ends; axial area linear; central area large, quadrate, united to the wide longitudinal lines; striz parallel, smooth, 8 in 10 n. Long Island (Lewis); Smith’s Island, Delaware River. Pl. 21, Fig. 10. NEIDIUM PFITZER (1871) (neidion, dim. of naus, a boat) Valve linear or lanceolate; median fissures turned in opposite directions, terminal fissures appearing bifurcate (?); strie transverse, usually oblique, finely punctate, crossed by one or several longitudinal blank lines. Chromatophores, two, lying on the girdle side, in cell division each forming a partially divided pair. A large pyrenoid is said to be found in the middle of each chromatophore, but Mereschkowsky states that the pyrenoids are absent, but that in N. affine four elico- plasts are always seen in the centre of the frustule. A genus easily recognized by the peculiar terminal and median fissures and by the yellowish or brownish color of the valves when dry, darker than in Caloneis. NEIDIUM AFFINE (EHR.) PFITZER Valve linear, with protracted, sub-rostrate or capitate ends. Navicula affinis Ehr. NEIDIUM AFFINE VAR. GENUINA FORMA MAXIMA CL. Strie, 14 in 10 », punctate, oblique in the middle, convergent at the ends; puncta, 15 in 10 zu. L. 238 yp. Pensauken, N. J. (artesian well). Pi. 21, Fig. 11. Var. genuina forma minor Cl.—L. 26 yu; strie, 24 in 10 p. Brandywine Creek. Pl. 21, Fig. 12. NEIDIUM AFFINE VAR. AMPHIRHYNCUS (EHR.) CL. Valve linear, with protracted capitate ends; strie transverse, interrupted by several longitudinal lines. Willistown, Pa. Pl. 21, Fig. 13. NEIDIUM AMPHIGOMPHUS (EHR.) PFITZER Valve with parallel margins and cuneate ends; strie transverse, interrupted by several longitudinal lines; central area widened transversely. Navicula amphigomphus Ehr. ‘ Wissahickon. Pl. 21, Fig. 14. NEIDIUM PRODUCTUM (WM. SM.) CL. Valve linear, elongate, with capitate apices; strix slightly oblique; longitudinal lines marginal; axial area very narrow, central area small. Navicula producta Wm. Sm. Newtown Square. Pi. 21, Fig. 16. 84 THE DIATOMACE OF PHILADELPHIA AND VICINITY NEIDIUM IRIDIS (EHR.) CL. Valve linear or lanceolate-elliptical, with sub-cuneate or rounded ends; striz oblique, about 18 in 10 u; central area orbicular. Navicula iridis Ehr. Navicula firma Kuetz. Willistown, Pa.; Middletown, Delaware Co., Pa. (Palmer). Pl. 21, Fig. 17. The form here figured is probably the variety ampliata (Ehr.) Cl. with less acute apices and more elliptical outline. The species occurs in many variations, the larger being found northward, especially in the peat deposits of New England. NEIDIUM HITCHCOCKII (EHR.) CL. Valve linear, with triundulate margin and cuneate ends; stri@ transverse, oblique. Navicula hitchcockii Ehr. Pavonia, N. J. (artesian well); Kirkwood Pond, N. J. Pl. 21, Fig. 15. DIPLONEIS EHR. (1840) (diplos, double) Valve elliptical or panduriform; median line enclosed in strongly siliceous horns cor- responding to the lyre-shaped areas of Navicula lyra but never punctate; central nodule, quadrate; valve costate, or striate, or both; between the horns and the outer part are thinner spaces or sulci, and, in some species, outside of the sulci are narrow spaces known as lunule. Chromatophores, two, upon the girdle or the valves. Pyrenoids have been found in one species only, D. interrupta. DIPLONEIS ELLIPTICA (KUETZ.) CL. Valve elliptical; central nodule large; sulci-narrow, curved, close to the horns; striz punctate, in rows radiating more and more toward the ends. Variable in size and in the coarseness of puncta which are from 10 to 13 in 10 u (Cleve). Cleve describes D. ovalis Hilse as having the central nodule rounded, but otherwise about the same as D. elliptica, and as equivalent to Navicula ovalis A. Schmidt (Atlas, Pl. 7, Figs. 33 to 36). Very common in fresh water and occasional in brackish. Pl. 20, Fig. 14. DIPLONEIS SMITHI (BREB.) CL. Valve elliptical; central nodule not broad; furrows evenly curved on the outer edge, crossed by costz and doub'e oblique rows of alveoli. Variable in size and in the curvature of the furrows. - Cleve forms a new species, D. major, of the large form figured by Schmidt (Atlas, Pl. 7, Figs. 18, 19, 21 and 22), stating that the structure is much coarser and the form is !arger with broad furrows. In the specimen here figured the size is median and the furrows are as in D. major. Marine and brackish. Common. Pl. 20, Fig. 17. THE DIATOMACE OF PHILADELPHIA AND VICINITY 85 DIPLONEIS CRABRO VAR. PANDURA (BREB.) CL. Valve constricted, segments tongue-shaped; central nodule small; horns narrow, nearly parallel, with a row of large puncta; costs, 4 in 10 u, convergent in the middle, radi- ating at the ends, alternating with a double row of puncta, 11 in 10 u. Pavonia, N. J. (artesian well). Pl. 20, Fig. 4. DIPLONEIS CRABRO VAR. EXPLETA (A. 8.) CL. Valve slightly constricted, segments tongue-shaped; costze robust, 5 or 6 in 10 yu, alter- nating with double rows of rather coarse puncta. L. 56 u. Port Penn, Delaware River. Pl. 20, Fig. 15. DIPLONEIS CRABRO VAR. PANDURELLA CL.? Valve constricted, the lobes elliptica.; central nodule large, with horns parallel in the middle, convergent at the ends; furrows wide, with faint cost; no lunula; costx parallel in the middle, radiate at the ends, 9 in 10 y, alternating with very fine double rows of puncta (not shown in the figure). L. 65 yp. Blue clay. Pl. 20, Fig. 13. DIPLONEIS CRABRO VAR.? Valve constricted, segments elliptical; costz, 8 in 10 uw, converging in the middle, radiating at the ends; horns narrow; furrows wide, costate; lunule indistinct. L. 75 p. Resembles var. pandurella except in the convergence of the costz and in the lunula. Squan River. Marine. Pl. 20, Fig. 9. DIPLONEIS FUSCA VAR. DELICATA (A. S.) CL. Valve elliptical; furrows broad, crossed with rows of faint coste and alveoli; costa, 6 or 7 in 10 y; alveoli, 10 in 10 y, in short, irregular, longitudinal rows. L. 84 u. Port Penn, Delaware River. Pl. 20, Fig. 11. DIPLONEIS GRUENDLERI (A. 8.) CL. Valve constricted, segments tongue-shaped, often unequal; horns broad, divergent in the middle; furrows narrow; cost transverse, crossed by from 3 to 7 longitudinal costz, interrupted in the middle at the border. Blue clay. Pl. 20, Figs. 7 and 8. DIPLONEIS- PUELLA (SCHUM.) CL. Valve elliptical, sometimes orbicular; furrows very narrow; striz, 20 in 10 y, indistinct. L. 15 pz. Diploneis elliptica var. minutissima Grun. Shark River, N. J. . Brackish. Pl. 20, Fig. 12. DIPLONEIS EXCENTRICA, N. SP. Valve elliptical; central nodule quadrate; furrows of the same width throughout, nearly parallel; costze radiating toward the ends, 10 in 10 y, indistinct on the furrows, alternating with alveoli, 7 in 10 y, in irregular, longitudinal lines. One side of the valve is one and a half times the width of the other. L. 49 nz. 86 THE DIATOMACE OF PHILADELPHIA AND VICINITY I can find neither description nor figure of any species to which I can ascribe this form. It approaches D. elliptica. The alveoli are quite distinct and distant from each other. Brackish water. Very abundant in a gathering from Squan River, N. J. Pl. 20, Fig. 10. DIPLONEIS OCULATA (BREB.) CL. Valve elliptical; strie radiate at the ends, about 20 in 10 p, coarsely punctate. L.23 yp. Fresh water. Pl. 26, Fig. 7. The figure is drawn from Brébisson’s original material in H. L. Smith’s Type Slide No. 299. Navicula oculata Bréb. Reported from New Jersey. I have not seen this species in this locality. Navicula oculata, referred to by Kain as occurring in Shark River, is not this form. DIPLONEIS GEMMATA (GREV.) CL. Valve oblong-linear, with cuneate ends and parallel or slightly concave sides; central nodule large; horns parallel; furrows about one-third the width of the valve. Coste about 5 in 10 y, alternating with double rows of fine puncta; short costz occur along the borders of the horns. Port Penn, Delaware River. Pl. 20, Fig. 16. DIPLONEIS CAMPYLODISCUS (GRUN.) CL. Valve suborbicular; central nodule quadrate; horns divergent; costz, 6 in 10 y, alterna- ting with double rows of alveoli; furrows broad, costate near the horns. Differs from Cleve’s description in having 6, instead of 4, cost in 10 yp. Pensauken, N. J. (artesian well). Rare. Pl. 20, Fig. 6. MASTOGLOIA THWAITES (1856) (mastos, a breast, and gloios, gelatinous, referring to the “‘mamillate cushion” in which the frustules are often immersed) Frustule rectangular. Valves similar, naviculoid. Central and axial areas usually narrow or indistinct; strie punctate, parallel in the middle. On each side, between the valve and the zone, is a septate plate. ANALYSIS OF SPECIES Ime yc 52 aes Boer at a aerate A deh a ciao ical Gi Oa ate das kinsmanii Striz not interrupted: Sees Loculi, five, or less... 2... eee eee ee eee eee ~exigua _ more than five, equal, ending at distance from the ends smithii — ending near the ends, distinct..............---..--. lanceolata indistinct..........-.----.-... elegans Very NUMEROUS. 650d cae ce rebau aie eeeeeeasesese apiculata unequal. ..... ie ade ge Matha e ante Nematic tiee angulata THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 87 Karsten states that there are two chromatophores, each of which extends from the middle of one valve to the end and down the middle of the other valve. Mereschkowsky says, however, that there are four plates or chromatophores, sometimes on the valve, some- times on the zone, according to the species, and that two long pyrenoids unite the two opposite chromatophores. MASTOGLOIA KINSMANIL LEWIS Valve lanceolate-elliptical, with sub-rostrate ends; loculi more numerous than in M. angulata but less than in M. apiculata, the middle ones larger. Median line with a sulcus on each side; central area quadrate. Mastogloia braunii Grun. (According to Cleve). Atlantic City. Pl. 17, Fig. 16. MASTOGLOIA EXIGUA LEWIS Valve elliptical- or linear-lanceolate; loculi, 2-5, usually 3, larger in the middle and rounded; central space small; strise, 20-24 in 10 p. Along the coast. Pl. 17, Fig. 24. MASTOGLOIA SMITHII THWAITES Valve lanceolate, sub-rostrate; loculi forming a wide band ending at a distance from the ends; strie transverse, with puncta forming longitudinal rows; central area rounded or transversely elliptical. Along the coast. Pl. 17, Fig. 19. MASTOGLOIA LANCEOLATA THWAITES Valve lanceolate, with sub-rostrate apices; loculi very numerous; median and central areas indistinct; striz, 19 in 10 u, punctate, convergent at the ends. Along the coast. Pl. 17, Fig. 18. MASTOGLOIA ELEGANS LEWIS Valve lanceolate, acute; loculi indistinct or rudimentary, extending to the ends; cen- tral area apparently quadrate, sometimes indistinct; puncta distinct, 15 in 10 p, in trans- verse and longitudinal rows. Along the coast. Common. Pl. 17, Fig. 20. MASTOGLOIA APICULATA WM. SM. Valve elliptical-lanceolate, sometimes with slightly produced apices; median line between two ribs; central space very small; loculi numerous; puncta in slightly radiating rows and in longitudinal lines. Along the coast. Pl. 17, Figs. 21, 22, 23. MASTOGLOIA ANGULATA LEWIS Valve elliptical, with produced apices; loculi usually less than 12, unequal, the larger in the middle; strie, 12 in 10 u, puncta in decussating rows. ‘Differs from apiculata in its more broadly elliptical shape, the smaller number of its loculi and the angular character of its striation”’ (Lewis). 88 THE DIATOMACE OF PHILADELPHIA AND VICINITY Considered by Cleve as synonymous with M. apiculata Grun., not Wm. Smith, and by De Toni as synonymous with M. apiculata Wm. Sm. In any case, M. angulata Lewis is not the same as M. apiculata Wm. Sm., the loculi of which are equal. Atlantic City. H. L. Smith T. 8. No. 211. Pl. 17, Fig. 17. STAURONEIS EHR. (1843) (stauros, a cross, and neis (naus), a boat) Frustules free, sometimes geminate; valve as in Navicula but with a stauros. Cell contents as in Navicula. Mereschkowsky, however, says that the chromatophores always contain more pyrenoids than are found in Navicula. Heinzerling gives the number as two to four in each chromatophore. Cleve includes under Navicule Microstigmatice all species of Stauroneis, Pleuro- stauron, Schizostauron, certain Schizoneme and Navicule. As a matter of convenience, and because I have already included certain Schizoneme and Scoliopleura under Navicula, and because of the small number of species in our locality, I have arranged them under the three divisions of Cleve as follows: Stauroneis.—Forms having a true stauros, without diaphragms. Pleurostauron.—Forms like Stauroneis but with diaphragms at the ends. Schizostauron.—Forms having a bifid stauros. STAURONEIS PHCNICENTERON EHR. Valve lanceolate, obtuse; strie radiate, 18 in 10 y, distinctly punctate. L. usually 125 » but sometimes 200 pu. Common in fresh water. Pl. 27, Fig. 1. STAURONEIS ANCEPS EHR. Valve lanceolate, with rostrate or capitate ends; stauros in some cases does not reach the margin. The varieties are very numerous. Var. gracilis (Ehr.) Cl.—Valve lanceolate, striz very fine; margin of stauros striated. L. 100». Cape May, N. J. Pl. 27, Fig.-5. Var. amphicephala (Kuetz.) Cl.—Valve capitate at the ends; striw, 24in 104. L. 474. Fresh water. PI. 27, Fig. 7. Var. ?—Valve with produced ends; striz, 30 or more in 10 p. L.104y. Willistown, Pa. Pl. 27, Fig. 4. Var. ?—Valve with produced ends; striz, about 28 in 10 u, punctate. L. 47». New- town Square. Pl. 27, Fig. 8. Var. ?—Valve with produced ends; stria, 22 in 10 yu, showing a tendency to form longitudinal rows of puncta as in Stauroneis stodderi Greenleaf, but the rows are not so evident. L.60 4. Pavonia, N. J., artesian well. Pl. 27, Fig. 9. STAURONEIS FRICKEI VAR. ANGUSTA N. VAR. Valve lanceolate, gradually tapering to the obtuse ends; terminal fissures prominent, forking at a distance of 7 » from the ends. Frustules frequently geminate. L. 173 p. Newtown Square. Rare. Pl. 26, Fig. 18. Near Stauroneis frickei A. S. (At'as, Pl. 242, Fig. 16), except that the stauros is narrow at the margin. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 89 STAURONEIS SALINA WM. SM. Valve lanceolate, obtuse; stauros narrow, with short, scattered strie at the margin, 18 in 10 », punctate. L. 65 u. Along the coast. Common. Pl. 27, Fig. 6. STAURONEIS LEGUMEN EHR. Valve elliptical-lanceolate, inflated in the middle, with produced sub-capitate or ros- trate ends separated by diaphragms. Stauros wide, striated at the margins; axial area very narrow; strie radiate, about 26 (?) in 10 u, punctate. L. 28 up. Pavonia, N. J., artesian well. Pl. 39, Fig. 15. In Cleve’s description and Van Heurck’s figure, the median inflation is ‘‘not larger than the others.”” In the present form the median inflation is wider. STAURONEIS ACUTA WM. SM. Valve rhombic-lanceolate, obtuse; a diaphragm at each end; stauros widened outwards; striz, 15 or 16 in 10 yn, punctate. L. 130 pz. Blue clay. Pl. 27, Fig. 2. STAURONEIS AMERICANA A. S. Valve elliptical-lanceolate, obtuse; striw, 14in 10 yp. L. 119 up. Pavonia, N. J., artesian well. Rare. The only specimen found is asymmetrical with respect to the transverse axis. On Plate 40, Fig. 4, is illustrated an abnormal form of Stauroneis, apparently near S. acuta, having an elongated central nodule and radiating, curved and coarsely punctate striz. Blue clay. STAURONEIS SMITHII GRUN. Valve lanceolate, inflated in the middle and at the ends, which have diaphragms and are produced into rostrate apices; stauros reaching the margin; strie parallel, about 25 in 10 » (28 to 30, Cleve), distinctly punctate. Not uncommon in meadow pools near Newtown Square. Pl. 27, Fig. 11. STAURONEIS CRUCICULA (GRUN.) CL. Valve lanceolate, with obtuse, produced ends; stauros bifid; strie, 24 in 10 yu, oblique, parallel to the branches of the stauros, closer at the ends, punctate. L. 32 u. Newtown Square. East Park Reservoir. Rare. Pl. 27, Fig. 10. NAVICULA BORY (1826) (dim. of navis, a boat) Valve linear to elliptical; ends acute, rounded, rostrate, capitate or truncate; axial area usually distinct; central area distinct, rounded or rarely extended into a transverse fascia; strie transverse or radiate, punctate; central area not dilated into a transverse stauros nor into horns. 90 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY The endochrome in the greater number of species consists of two chromatophores extending along the zone and sometimes partly over the valves. Sometimes, however, as in N. hennedyi, N. lyra and N. humerosa, the bands are on the valves. Certain species have four bands, others eight, and in one the endochrome is granular. (Mereschkowsky, l. c., p. 9 et seq.) Pyrenoids are usually absent. On account of the diversity of the chro- matophores, Mereschkowsky considers the genus not homogeneous. The difficulty of arranging groups according to the cell contents, however, is so great that, for the present, the species must be described by the usual characteristics of the valves and divided as follows, according to Cleve, to the extent of employing the classification of all Naviculoid forms as applicable, especially to the species of Navicula. Van Heurck’s analysis includes Pinnularia, Trachyneis, Diploneis, Caloneis, Neidium and Anomceoneis, which are here separated, while N. lyra and N. hennedyi are placed in different groups, although they are closely related. In other respects Cleve’s divisions correspond, to some extent, to those of Van Heurck. The genus Navicula at one time included the following: Dictyoneis, Pleurosigma, Gyrosigma, Caloneis, Neidium, Diploneis, Frustulia, Trachyneis, Anomceoneis, Pinnularia and Stauroneis, and few forms with a raphe escaped. For this reason the diagnosis of the present genus is somewhat limited. Pleurosigma and Gyrosigma differ from Navicula in their outline, Dictyoneis in the double stratification, Caloneis in the marginal lines, Neid- ium in the median and terminal fissures, Diploneis in the horns, Frustulia in the terminal nodules, Trachyneis in the stratification of the valve, Anomceoneis in the longitudinal arrangement of the puncta, Pinnularia in the smooth coste and Stauroneis in the stauros. As the object of the present work is to aid the student of local forms in the identifi- cation of species by the briefest methods, the further discussion of the reasons for classi- fication will be left for his gratification in referring to the authorities on the subject. Poncrataz CLevE Valve elliptical to lanceolate; central nodule not stauroid or continued into lyriform spaces; strie distinctly or coarsely punctate, in radiate rows. NAVICULA MACULATA (BAIL.) CL. Valve lanceolate-elliptical, with produced or sub-rostrate ends; axial arca narrow, wider near the ends and dilated to a rounded, transverse central area; strize radiate, 6 in 10 ph, puncta, 7 in 10 y, in irregular, longitudinal rows. L. 90 to 120 u (Cl.). Stauroneis maculata Bail. ea Navicula fischeri A. S. Blue clay. Along the coast, especially southward. Pl. 24, Fig. 1. NAVICULA LATISSIMA GREG. Valve oblong-elliptical or elliptical-lanceolate, with sub-cuneate ends; axial area lan- ceolate, widened in the middle to an orbicular space; strie radiate, 7 in 10 p, puncta, 11 in 10 p, the median strie alternating with short stria along the sides. L. 50-150 yu (Cl). Blue clay. Pavonia, N. J., artesian well. Pi. 24, Fig. 3. : THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 91 NAVICULA LATISSIMA VAR. ELONGATA (PANT.) CL. Valve elliptical-lanceolate, with rounded ends; strix and puncta closer than in the type form; axial area narrow, widened in the middle; terminal fissures hook-shaped, turned in different directions. Navicula humerosa var. elongata Pant. Fossil at Buckshutem, N. J. Pl. 24, Fig. 5. NAVICULA FUCHSII PANT. Valve elliptical, with slizhtly produced apices; axial area wide, lanceolate; central area orbicular; striz alternately longer and shorter in the middle, 10-12 in 10 »; puncta on the border of the axial area larger, elongated; median fissures incrassate. Navicula humerosa var. fuchsii (Pant.) Cl. Navicula (latissima var.?) fuchsti Pant. Port Penn, Delaware River. Pl. 24, Fig. 6. NAVICULA HUMEROSA BREB. Valve lanceolate-elliptical or oblong-elliptical, with sub-cuneate or sub-rostrate ends; axial area narrow, lanceolate; central area rounded, somewhat transverse; terminal fissures hook-shaped, in the same direction; central pores incrassate; strie, 11 in 10 u, the middle alternately longer and shorter, closer at the ends. L. 60-86 yu. Variable in size, outline and fineness of striation. N. monilifera Cleve (N. granulata Bréb.) differs in having coarser striae. Blue clay. Along the coast. Pl. 25, Fig. 5. NAVICULA PUSILLA WM. SM. Valve ovate-elliptical, with rostrate or sub-rostrate ends; axial area narrow; central area elliptical; strie radiate, 10-12 in 10 u in the middle where they are longer and shorter alternately, closer at the ends; median fissures somewhat incrassate, terminal in the same Girection. L. 47 pz. Smith’s Island, Delaware River. Pl. 25, Figs. 4, 6? Cleve gives the striz bg 13-18 in the typical form, and 11-13 in varieties. In the form here figured the striation is as stated by De Toni, but is about 19 at the ends. Fig. 6 appears to be a small form of N. pusilla, near lanceolata Grun., at least accord- ing to the figure in ‘‘Arctic Diatoms,” but not Gregory’s figure. It occurs rarely in fresh water at Newtown Square. It may bea small form of N. punctulata and, if so, is probably accidental, as the material is entirely fresh-water. NAVICULA PUSILLA VAR. SUBCAPITATA N. VAR. Valve elliptical with rostrate-capitate and truncate ends; striz about 12 in 10 » in the middle where they are unequal; axial area narrow, slightly widened in the middle; central pores incrassate, terminal fissures in the same. direction. Differs from type in out- line and centre. Pavonia, N. J., artesian well. Rare. Pl. 25, Fig. 8. 92 THE DIATOMACE OF PHILADELPHIA AND VICINITY NAVICULA DELAWARENSIS GRUN. Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, lanceolate, widened in the middle; strice about 10 in 10 » in the middle, much closer at the ends; puncta in the middle, 9 in 10 y, closer and much smaller at the ends. L. 58-95 yu. Cleve (Le Diatomiste, Vol. 2, p. 14) states that this form is very near N. pusilla but is much larger. Specimens from Smith’s Island measure 58-65 y, from Wildwood, 95 yu in length. Pl. 25, Fig. 3. NAVICULA PUNCTULATA WM. SM. Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, central area rounded; striz, 11 in 10 p, closer at the ends, a few shorter in the middle; puncta, 10 in 10 pw. L. 544. . Navicula marina Ralfs. Port Penn, Delaware River (brackish water). Pl. 25, Fig. 9. ‘Although this species is described as marine in the Synopsis of Prof. Smith, I have never found it in purely marine localities” (Donkin). NAVICULA PUNCTATA VAR. ASYMMETRICA LAGERSTEDT Valve lanceolate, with rostrate ends; axial area narrow, central area transverse, irreg- ular; strie radiate, punctate, 12in 104. L. 36 x. Navicula amphibola Cleve. Blue clay. Pl. 27, Fig. 15. NAVICULA BRASILIENSIS VAR. BICUNEATA CL., FORMA CONSTRICTA Valve oblong-elliptical, slightly constricted, with cuneate-rostrate ends; axial area narrow; central area dilated transversely and unilaterally; strie, 9 in 10 4; puncta closer at the border and in irregular longitudinal rows in the middle; terminal fissures small, hook- shaped, turned in the same direction. L. 93 yu. Corresponds closely to Cleve’s variety except in the constriction. Blue clay. Pl. 25, Fig. 2. NAVICULA LACUSTRIS GREG. Valve lanceolate, sub-acute; axial area narrow; central area orbicular; stri# radiate, 14 in 10 yz, punctate, the median puncta sometimes more distant than the others. Blue clay. Rare. Pl. 27, Fig. 12. LyRAT& C1. Valve elliptical or elliptical-lanceolate; strise punctate, transverse; axial area narrow or indistinct; central area expanded on each side into lyre-shaped or horn-like blank spaces. oes, NAVICULA PRETEXTA EHR. Valve elliptical; lateral areas not regular, with scattered puncta; strie radiate, 5 or 6 in 10 y; puncta, 7 or 8 in 10 yw; along the axial area, a single or double row of puncta; at THE DIATOMACE OF PHILADELPHIA AND VICINITY 93 the middle of the border, on each side, two strie approach each other closely with a short stria between them; terminal fissures small, in the same direction. L. 120 u. Port Penn, Delaware River. PI. 24, Fig. 2. While variable in size and striation, approaching N. hennedyi, this species, as here figured, is found in the Miocene and later deposits and is extant in most parts of the world. NAVICULA IRRORATA GREY. Valve oblong-elliptical, with cuneate-rostrate ends; strie, 7 or Sin 10 4, puncta, 7 in 10 »; axial area bordered by puncta in unequal, transverse rows. L. 84 u. Blue clay. Rare. Pl. 24, Fig. 4. NAVICULA HENNEDYI WM. SM. Valve elliptical; areas semilanceolate; striz about 11 in 10 », sometimes longer and shorter on the margin; short rows of transverse striw along the axial area. Blue clay. Pl. 25, Fig. 12. Var. circumsecta Grun.—As in the type but with the lateral areas faintly striate or punctate. Var. manca A. S.—Valve lanceolate-elliptical, the lateral areas narrow and conver- gent toward the ends; short rows of transverse strize along the axial area; strix, 9 in 10 y; central pores incrassate. ; Blue clay. Pl. 25, Fig. 11. NAVICULA LYRA EHR. Valve elliptical, with rounded, sub-rostrate or sub-cuneate ends; lateral areas narrow; strie, 6 to 14 in 10 » (CI.), punctate. L. 50-180 up. Var. ehrenbergit Cl—Lateral areas constricted in the middle, divergent at the ends. Cleve refers to Schmidt, Atlas, Pl. 2, Fig. 25, which is not divergent at the ends. Along the coast. Pl. 25, Fig. 10. A narrower form occurs which has the areas divergent. Var. ?—Valve elliptical, lateral areas narrow, convergent at the ends with short rows of punctate strie; marginal striz, 10 in 10 », punctate. L. 60 x. Squan River, N. J. Pl. 20, Fig. 5. Var. dilatata A. S.—Valve elliptical, rostrate; lateral areas convergent in the middle and nearly parallel or convergent at the ends. Blue clay. Pl. 25, Fig. 13. N. lyra is exceedingly variable in outline, fineness of striation and in the lateral areas. Intermediate forms occur approaching N. hennedyi and N. spectabilis. In N. hennedyi the lateral areas are broad, semilanceolate, not narrowed in the middle. In N. spectabilis the lateral areas are broad and narrowed in the middle. In N. lyra the lateral areas are narrow and either constricted or not in the middle. In many forms in 94 THE DIATOMACEA OF PHILADELPHIA AND VICINITY these three species the lateral areas are more or less striated or punctate. Cleve does not consider this a distinction of any importance, although certain varieties are founded upon it. All three species are very common in the blue clay and along the coast, but their varieties are too numerous to describe or figure. NAVICULA SPECTABILIS VAR. EMARGINATA CL. Valve elliptical; lateral areas broad, narrowed in the middle, delicately striated; mar- ginal strie,10in 10 yu. L. 70 un. Blue clay. Pl. 25, Fig. 7. NAVICULA PYGMHA KUETZ. Valve elliptical, appearing hyaline; axial and central areas faint; lateral areas con- vergent in the middle; strize indistinct, about 25 in 10 4. L. 23 uz. Brandywine Creek (Palmer). Pl. 27, Fig. 23. DecussaT#& Cu, Valve elliptical or lanceolate; axial area narrow; central area small; striae punctate, in transverse and oblique, curved rows. NAVICULA PLACENTA EHR. Valve elliptical, with short, rostrate-capitate ends; axial area narrow; central area elliptical; strie in two directions, the transverse about 22 (to 27, Cl.) in 10 yn, the oblique striz crossing in both directions in curved lines appearing ‘‘coarser than the trans- verse” (Lewis). A very peculiar species which, as Cleve remarks, seems not to be allied to any other. L. about 35 y, quite constant in size. It is reported from Finland, Scotland, Hungary and New Zealand. Dr. Lewis found it in the Delaware River. It is occasional in the Schuyl- kill River and the blue clay, and very abundant on Marchantia and mosses on the wet rocks of the upper Wissahickon (F. J. Keeley). - Pl. 27, Fig. 17. LingotatT#£ Ct. Valve more or less lanceolate; axial area narrow or indistinct; stria radiate or parallel, lineate, that is, with the puncta closer than the stria. NAVICULA RADIOSA KUETZ. Valve lanceolate with sub-rostrate apices; axial area indistinct; central area small; strise radiate in the middle, from 6 to 8 in 10 u, and convergent at the ends, about 12 in 10u. L. 47 zp. ; Very common in fresh water. Pl. 26, Fig. 17; Pl. 40, Fig. 9. NAVICULA PEREGRINA EHR. Valve lanceolate, obtuse; axial area narrow; central area large, rounded or slightly irregular ; striz coarse in the middle, 5 in 10 u, radiate; convergent at the ends, 7 or 8 in 10 xz. Abundant in brackish water. Delaware River. Pl. 26, Fig. 20. THE DIATOMACEE OF PHILADELPHIA AND VICINITY 95 NAVICULA CYPRINUS (WM. SM.) Valve lanceolate, slightly gibbous in the middle, sub-cuneate at the ends; axial area narrow; central area small; strie radiate in the middle, 10 in 10 y, with shorter, transverse strie intermediate; transverse at the extreme ends. L. 82 yu. Navicula digito-radiata var. cyprinus (Ehr. ?) Wm. Sm. Whether the form here figured is Ehrenberg’s or not, it is the species known as Pinnularia cyprinus Ehr. of Wm. Smith. Common in Shark River, N. J. Pl. 26, Fig. 21. NAVICULA REINHARDTII GRUN. Valve elliptical or elliptical-lanceolate, with broad, rounded ends; axial area narrow, widened at the ends to the width of the valve; central area widened transversely to an irreg- ular, quadrate space; striz coarse, 8 in 10 yu, distinctly lineate, alternately longer and shorter in the middle, radiate, nearly transverse at the ends. L. 59 zu. Blue clay. Rare. Pl. 26, Fig. 22. NAVICULA LANCEOLATA VAR. ARENARIA (DONK.) CL. Valve lanceolate; axial area very narrow or indistinct; central area small, rounded; striz radiate, 11 in 10 » in the middle, closer at the ends. L. 47-54 yu. Navicula arenaria Donk. Shark River, N. J. Pl. 26, Fig. 23. NAVICULA SALINARUM GRUN. Valve elliptical-lanceolate with produced sub-capitate or rostrate ends; strie radiate in the middle, longer and shorter; transverse at the ends, lineate. L. 32 » Atlantic City, N. J. Pl. 26, Fig. 24. NAVICULA VIRIDULA VAR. ROSTELLATA KUETZ. Valve lanceolate with rostrate ends; axial area very narrow, central area orbicular; strie radiate in the middle, about 12 in 10 », convergent at the ends and closer. L. 43 p. Common in fresh water. Pl. 26, Fig. 16. NAVICULA GRACILIS VAR. SCHIZONEMOIDES (EHR.) Vv. H. Valve lanceolate, obtuse; axial area widened in the middle; strise radiate in the middle, about 12 in 10 y, transverse or slightly convergent at the ends. L. 45-60 ». Occurs in gelatinous tubes; usuaily found free. Colletonema neglectum Thwaites. Fresh water. Pl. 26, Fig. 19. NAVICULA RAMOSISSIMA (AG.) CL. e¢ Valve lanceolate, sub-acute; axial area very narrow; central area scarcely widened; striz, 12 in 10 y, parallel throughout. L. 45 n. Micromega ramosissimum Ag. Schizonema smithit Kuetz. (not Ag.). East River, N. Y. Pl. 26, Fig. 14. c 96 THE DIATOMACE OF PHILADELPHIA AND VICINITY NAVICULA ANGLICA RALFS Valve elliptical, with sub-capitate or rostrate ends; axial area narrow, central area small; strie radiate, 12-13 in 10 p, distinctly punctate. L. 26 pn. Fresh water. Pl. 26, Fig. 26. NAVICULA GASTRUM EHR. Valve elliptical, with rostrate ends; axial area narrow, central area transverse or irreg- ular; strize radiate, 9 in 10 » in the middle. L. 26 n. The form here figured approaches N. anglica. Kirkwood Pond, N. J. Pl. 26, Fig. 25. NAVICULA DICEPHALA WM. SM. Valve linear, with rostrate or rostrate-capitate ends; axial area narrow, central area rectangular, transverse; strie radiate, 12in 10 yn. L. 32 p. Fresh water. Pl. 27, Fig. 16. NAVICULA HUMILIS DONK. Valve elliptical, with broad, rostrate ends; axial area narrow; central area small; strie radiate and distant in the middle, convergent at the ends, coarse, appearing costate, averaging 9in 10 y. L.19y4. As Donkin states, the strie are ‘‘very conspicuous.’ Navicula hungarica var. capitata (Ehr.) Cl. Navicula globiceps Lagerstedt, according to Cleve. Willistown, Pa. Pl. 27, Fig. 24. NAVICULA PINNATA PANT. ? Valve lanceolate, obtuse; axial area narrow, widened in the middle; strie coarse, 7 in 10 » in the middle, radiate, 10 in 10 » at the ends and transverse, indistinctly lineate. L. 40 p. Near Navicula ardua Mann (Diat. Albatross Voy., Cont. U. 8. Nat. Herbarium Vol. 10, Part 5, p. 336, Pl. 53, Fig. 2) which, however, is said'to have ‘‘strictly unbeaded costz.”’ Pavonia, N. J., artesian well. Pl. 27, Fig. 20. NAVICULA PENNATA A. S. Valve lanceolate, acute; axial area narrow; central area quadrate, transverse; strie radiate, coarse, 5 in 10 y, lineate. L. 68-95 yp (Cleve). Pavonia, N. J., artesian well. Pl. 27, Fig. 22. NAVICULA INFLEXA GREG. Valve slightly elliptical-lanceolate, sub-acute, smooth at the ends; axial area narrow, widened in the middle; strie radiate, 11 in 10 y, lineate. Frustule in zone view constricted in the middle. L. 28-45 uz. Common along the coast. Pl. 27, Figs. 18 and 19. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 97 NAVICULA OBLONGA KUETZ. Valve linear-lanceolate, with broad, rounded ends; margin sometimes undulate; axial area narrow; central area large, orbicular; strix in the middle distant, radiate, convergent at the ends and curved or sharply bent, 7 in 10 u, lineate. L. 70-200 » (Cleve). Blue clay. Occasional in fresh water. Pl. 27, Fig. 21. NAVICULA HASTA PANT. Valve lanceolate, gently tapering to the obtuse, produced ends; axial area lanceolate, widened to an orbicular space in the middle; strie radiate, the median coarse and quite distant, 5 in 10 », becoming closer at the ends where they are 12 in 10 y, lineate. The dis- tance between the median striz gives the appearance of a stauros. Occasional in the blue clay. Pl. 27, Fig. 13. NAVICULA HASTA VAR. PUNCTATA N. VAR. Valve as in type but with strie in the middle distinctly punctate and reaching the median line. Greenwich Point, Philadelphia. Pl. 27, Fig. 14. NAVICULA RHYNCOCEPHALA KUETZ. Valve lanceolate, with produced ends; axial area indistinct; central area small,'rounded; striz radiate in the middle, convergent at the ends, 10-11 in 10 », punctate. L. 42 p. Fresh water. Common. Pl. 31, Fig. 8. NAVICULA CRYPTOCEPHALA KUETZ. Valve lanceolate, with rostrate ends; axial area indistinct; central area small; stria, i6 in 10 y, lineate, radiate in the middle, convergent at the ends. L. 28 u. Common in fresh water. Intermediate forms occur between N. rhyncocephala and N. cryptocephala. Pl. 31, Fig. 9. NAVICULA LONGA (GREG.) RALFS Valve slender, rhombic, elongated, with acute ends; axial area indistinct; central area small; strie, 6 or 7 in 10 yu, radiate in the middle, elsewhere transverse; central pores closely approximate. L. 120 uz. New Rochelle, N. Y. Pl. 31, Fig. 10. Cleve refers this form to N. directa var. remota Grun. Some specimens are found in this locality showing the ‘generally twisted” median line mentioned by Gregory. oooe. MESOLELE Ct. Valve linear or elliptical; axial area narrow; central area quadmie; strie radiate, finely punctate. =e NAVICULA MUTICA KUETZ. 2 Valve ovate, elliptical or lanceolate; axial area narrow; central area dilated j into a stauros not reaching the margin; strix about 20 in 10 u, more distant in the middle, radiate, punctate. A punctum occurs on one side of the central nodule. 98 THE DIATOMACE OF PHILADELPHIA AND VICINITY Reported from New Jersey in fresh water. I have not found it. The figure is from a specimen from another locality. Pl. 26, Fig. 6. NAVICULA MINIMA GRUN. Valve broadly elliptical, 13-15 » in length; axial area narrow; central area small but with a quadrate pscudo-stauros which is striated; strie, about 28 in 10 y, radiate. Agrees closely with N. saugeri var. Grun. in V. H. Synopsis, Pl. 14, Fig. 16, said to be intermediate between N. minima and N. atomoides Grun. N. minima var. atomoides Grun. is smaller. , Common in water-troughs. Pl. 26, Fig. 13. NAVICULA PUPULA VAR. BACILLARIOIDES GRUN. Valve linear, with rounded ends; axial area linear, expanding on both sides near the ends of the valve, forming a transverse lunate space; central area small, apparently expanded into a stauros, which, however, is striated; strize, 18 in 10 y, at the middle, closer at the ends, punctate. L. 54 u. Pavonia, N. J., artesian well. Pl. 26, Fig. 9. BacILuares Cu. Valve linear or linear-elliptical, with broad ends; axial area narrow, the median line enclosed in siliceous ribs; striz finely punctate, more distant in the middle. NAVICULA BACILLUM EHR. Valve linear, with rounded ends; axial area enclosed in siliceous ribs and slightly ex- panded on each side at the ends; terminal nodules incrassate; central area small, elliptical; strie, 15 in 10 » in the middle, transverse, distinctly punctate, closer at the ends L. 47 uy. Fresh water. Pl. 26, Fig. 10. : Cleve describes the form as having slightly radiate striz in the middle. There is con- siderable difference in the descriptions of Cleve, Donkin, Grunow and Van Heurck, as also in all of the figures. » NAVICULA AMERICANA EHR. Valve oblong-linear, with rounded ends, sometimes slightly constricted; axial area about one-half the width of the valve, dilated in the middle; strie parallel in the middle, radiate at the encs, 15-16 in 10 ». A punctum is usually found in the central nodule. L. 55-154 up. Blue clay. Occasional in fresh water. Pl. 26, Fig. 8. DeEciPIENTES CL. Valve lanceolate, with obtuse ends; axial area narrow; central area orbicular; strie radiate in the middle and more distant. NAVICULA SEMEN EHR. Valve elliptic-lanceolate, with sub-rostrate, truncate apices; axial area narrow, sin- THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 99 uous; central area orbicular; terminal fissures small, hook-shaped; strize robust, 7 or S in the middle, clcser at the ends, indistinctly punctate or lineolate. Blue clay. Not common. Pl. 26, Fig. 11. Cleve states that this form belongs to the post-glacial deposits and is found living only in the Hartz Mountains. NAVICULA INTEGRA WM. SM. Valve lanceolate with triundulate margins and rostrate-apiculate ends; striw radiate, more distant in the middle, 20-23 in yu, punctate; axial area very narrow, central area rounded or elliptical. L. 33-43 u. Pavonia, N. J., artesian well. Common in Chester River, Md. Pl. 26, Fig. 5. MiIcnosTIGMATIC® CL. Valve lanceolate; axial area narrow; central area small, rounded; striz finely punctate, nearly parallel. (Includes here only the division Libellus.) NAVICULA TUMIDA (BREB.) CL. Valve lanceolate, with rounded ends; axial area narrow, central area elliptical; raphe slightly sigmoid; strie, 13 in 10 y, finely punctate, a few shorter in the middle. Scoliopleura tumida (Bréb.) V. H. Cape May, N. J. Pl. 25, Fig. 1. NAVICULA GREVILLEI (AG.) CL. Frustules in gelatinous tubes, rectangular; zone with numerous longitudinal divisions. Valve elliptical-lanceolate, obtuse; axial area narrow, central area small; striae lineate, about 18 in 10 u in the middle where they are slightly radiate and more evident, closer near the ends and transverse; median line with terminal pores distant from the ends. L. 60 p. Schizonema grevillei Ag. East River, N. Y. Pl. 31, Figs. 3 and 4. NAVICULA LIBELLUS GREG. Valve rhombic-elliptical, obtuse at the ends; axial area narrow, central rounded, small; strie punctate, slightly radiate, about 19 in 10 y; terminal fissures close to the ends, indistinct. L. 60 p. Cleve describes this form as having acute ends, while Gregory states that it is ‘“more obtuse and broader than N. rhombica.” Gregory’s Figure 101 apparently shows the ends acute, but he says that the valve view is ‘‘rhombic or elliptic-lanceolate, broad, with ob- tuse ends” (Diat. of the Clyde, p. 57, Pl. 6). Hackensack Swamp, N. J. Pl. 31, Fig. 5. : OrtHosTIcCHe® CL. Valve lanceolate or elongated; axial area narrow; central area sometimes apparently dilated into a stauros; stri# punctate, the puncta in transverse and longitudinal rows. 100 THE DIATOMACE OF PHILADELPHIA AND VICINITY NAVICULA CUSPIDATA KUETZ. Valve rhombic-lanceolate, with acute ends; axial area linear, narrow, not widened in the middle; strix transverse, 14-19 in 10 u (Cl.). L. 70-150 p. Blue clay. Not uncommon in fresh water. Pl. 26, Figs. 1 and 2. Fig. 2 represents an inner valve or stratum, with strong coste variable in size, formerly known as Surirella craticula Ehr. N. cuspidata var. ambigua (Ehr.) Cl.—Valve elliptical-lanceolate, with rostrate ends, smaller than the type and with finer striz. Crum Creek. Pl. 26, Fig. 3. NAVICULA SPICULA (HICKIE) CL. Valve narrow, lanceolate with acute ends; axial area narrow, central area dilated into a stauros reaching the margin; transverse strie, 25-29 in 10 yu, longitudinal closer. L. 50-130 (CL). Sometimes confused with N. crucigera. Stauroneis spicula Hickie. Newark, N. J. Pl. 26, Fig. 4. NAVICULA CRUCIGERA (WM. SM.) CL. Valve lanceolate, narrow, with acute apices; central nodule a stauros reaching the margin but crossed by two or three coarser striz; transverse striz, 12 in 10 », punctate, the puncta about 25 in 10 u. L. 80-100 » (Cl.). Frustules in gelatinous tubes or free. Schizonema cruciger Wm. Sm. Pl. 26, Fig. 15. Reported as occurring in New York Bay, but I have not seen it. The figure is from a specimen from another locality. - Minvuscu.e Cu. Valve lanceolate or elliptical, chiefly distinguished by the small size; axial area indis- tinct; central area small; strie radiate, very finely punctate. NAVICULA ATOMUS NZGELI Valve elliptical, 6-8 » in length; strie radiate, 26-30 u, closer near the ends; axial area linear, scarcely widened in the middle. Water-troughs and ditches. Probably common, but frequentiy not noticed because of its minuteness. A mounting medium of the highest refractive index, such as realgar, is required to resolve the striz. In the figure the striz are drawn a little coarser than they appear in most specimens. Pl. 26, Fig. 12. L&vVISTRIATE CL. Valve lanceolate, axial area distinct; central area orbicular ; Strie coarse, indistinctly punctate, approaching the cost of Pinnularia. THE DIATOMACE OF PHILADELPHIA AND VICINITY 101 NAVICULA YARRENSIS GRUN. Valve elliptical-lanceolate, with rounded ends; axial area lanceolate, widened in the middle; strie,5in 10 yu. L. 97 u. Cape May, N. J. Common. Pl. 25, Fig. 14. Fig. 15, a smaller form, 65 u in length; strie, 6 in 10 p. Fig. 16, 54 » in length; striw, 8 in 10 u (near var. valida Pant.). NAVICULA ELEGANS WM. SM. Valve elliptical-lanceolate, with produced ends; axial area very narrow, central area large, orbicular; stria strongly divergent in the middle, slightly, if at all, convergent at the ends, curved toward the margin, indistinctly lineate, 9in 10 yu. L. 95 z. Blue clay. Not rare. Pl. 31, Fig. 1. Navicula elegans var. cuspidata Cl.—Valve as in type form but smaller and with rostrate apices; strie, 10 in 10 y. L. 82 un. = Belmar, N. J. E Pl. 31, Fig. 2. if Cleve remarks that the type form is acute and the stria 9, while the var. cuspidata has 12 striein10y. In Fig. 1, Pl. 31, is represented a valve having 9 strix in 10 », but not acute, while Fig. 2, with but slight variation in strix, is more cuspidate. It is probable there are intermediate variations. NAVICULA PALPEBRALIS BREB. Valve elliptical-lanceolate, with acute apiculate ends; axial area broad, lanceolate; strize radiate, lineate, about 11 in 10 yu. L. 60 uz. Along the coast. Pl. 31, Figs. 6 and 7. On Plate 40, Fig. 5, isrepresented an abnormal form of Navicula in which the central pores are in a line transverse to the longitudinal axis and each raphe is curved in a line which almost returns to the centre. The puncta are in curved lines radiating from the rounded hyaline centre. Pavonia, N. J., artesian well. Weissflog has described valves of Navicula somewhat similar in punctation. PINNULARIA Ear. (1843) (pinnula, a small feather) Valve linear or nearly so, with rounded ends; axial area broad; central and terminal areas large; cost smooth, transverse or radiating, usually convergent at the ends. The coste are channels on the inside of the valve, closed, except in the middle where elliptical foramina, opening into the interior of the valve, give rise through their terminal margins to the two longitudinal lines on each side of the valve. The raphe begins as a groove in the side of the conical central nodule and continues as a cleft at right angles to the plane of the surface of the valve, in which case the raphe forms a single line; if the raphe is inclined to the valve surface, then two lines appear in projection, the upper and lower edges of the cleft. In some forms the surface of the edge of the raphe on one side is folded or grooved for a considerable distance, and the opposite edge is elevated into a ridge or 102 THE DJATOMACE OF PHILADELPHIA AND VICINITY tongue fitting into the groove. In such cases it is possible, in projection, to see the upper or outer edges of the raphe, the lower edges and the edges of the tongue and groove, thus showing four lines; sometimes, when the tongue and groove do not meet, six lines. The so-called inner channel is the part of the raphe on the inside of the tongue, and the so- called exterior channel is the part of the raphe on the outside of the tongue. If, in addition to this formation of the raphe, the plane of cleavage changes toward the terminal nodules, the lines will cross each other and, when two are superimposed, disappear altogether. For the careful examination of the raphe it is necessary to employ large forms, and it is advis- able to use nitrate of silver which remains in the raphe, and, as in slides mounted by Mr. F. J. Keeley, shows in a beautiful manner the entire outline of raphe and fissures. The terminal fissures owe their separation to the different directions taken by the two edges of the raphe on each side, one edge bending in a wide curve toward the end of the valve, show- ing two lines, the upper and lower edges of one side of the raphe when inclined to the plane of the surface, and the other edge of the raphe turning suddenly in an opposite direction and ending abruptly in a curve, giving rise to the appearance, by diffraction, of a punctum. Pl. 40, Figs. 13, 14 and 15. Endochrome consists of two chromatophores lying on the zones. Pinnularia is usually divided into the Majores, or larger, and the Minores, or smaller forms, the latter being further divided according to their strie. The following classification is chiefly that of Cleve. Majores.—Valve large, linear with parallel or slightly radiate strie and broad axial area. Gracillime.— Valve small, striz parallel or nearly so; axial area very narrow. Capitate.—Valve with capitate or rostrate ends; striz radiate. Divergentes.—Striz strongly radiate. Brevistriate—Strie short. Distantes.—Strie distant. Tabellarie.—Striz radiate in the middle, strongly convergent at the ends. Marine.—Marine forms. - = MAJORES PINNULARIA MAJOR (KUETZ.) WM. SM. Valve linear, usually slightly gibbcus in the middle and at the ends; raphe oblique; axial area less than one-third the width of valve, convergent at the ends; strie, 7 or 8 in 10 yn, radiate in the middle, convergent at the ends, crossed by a narrow band. L. ? to 300 u. Blue clay. Fresh water. Abundant at Middletown, Delaware Co. (T. C. Palmer). Pl. 28, Fig. 4. Fig. 9, Pl. 29, is one of a number of smaller forms which are difficult to determine, approaching P. viridis. = =. PINNULARIA MAJOR VAR. PULCHELLA N. VAR. —~ Valve strongly gibbous in the middle and gradually widened to the rounded ends; axial area broad, less than one-third the width of the valve, widened unilaterally in the middle; striz, 7 in 10 yu, crossed by a band nearly as wide as the length of the costa and scarcely distinct. L. 273 yu. THE DIATOMACE-® OF PHILADELPHIA AND VICINITY 103 The central nodule is scarcely evident, probably because it is not so thick as in other forms. ‘The outline is near to that of N. mesogongyla and certain forms of N. nobilis, differing from the latter in the median line, strize and band which is wider than that of P. latevittata var. domingensis Cl. Hammonton Pond, N. J. Pl. 28, Fig. 2. A very beautiful form which I cannot find described or figured. It does not appear to be N. major var. turgidula Cl., which has a narrow band. In the fossil deposit from Hop- kinion, N. H., valves occur similar in outline but smaller. PINNULARIA NOBILIS EHR. Valve slightly gibbous in the middle and at the ends; median line complex; striz, 4 or 5 in 10 yg, slightly convergent or parallel at the ends, crossed by a band one-third as wide as the length of the strie. L. ? to 350 up. Blue clay. Fresh water. Pl. 28, Fig. 1. PINNULARIA DACTYLUS EHR. Valve broad, linear, slightly gibbous in the middle; ends broad, rounded; median line not complex, sinuous; strie, 4 or 5 in 10 », crossed by a very broad band. L. ? to 300 u. Navicula gigas A. S. Blue clay. Fresh water. Pl. 28, Fig. 3. Forms occur which are with difficulty assigned to either nobilis or dactylus.. PINNULARIA DACTYLUS VAR. DARIANA (A. 8.) CL. Valve linear-lanceolate, obtuse; axial area broad, less than one-third the width of the valve; striz, 6 in 10 », crossed by a broad band. L. 220 u. Absecon, N. J. Pl. 29, Fig. 3. PINNULARIA DACTYLUS VAR. DEMERAR- CL. Valve elliptical-lanceolate, with sub-cuneate ends; axial area lanceolate, broad in the middle; median line flexuose; strie radiate throughout, 6in 10 yu. L. 150 zu. Blue clay. Pl. 29, Fig. 10. PINNULARIA GENTILIS (DONK.) CL. Valve linear, with rounded ends; axial area about one-fourth the diameter of the valve; strie radiate in the middle, convergent at the ends, 7 in 10 yu, crossed by a broad indistinct band. Fresh water. Not common. Pl. 29, Fig. 1. PINNULARIA TRIGONOCEPHALA CL. Valve linear, gibbous in the middle and at the cuneate ends; axia] area wider between the middle and the ends, dilated to an elliptical space in the middle; strix,6 in 10 yu. L. 145 p. Blue clay. Pl. 29, Fig. 8. 104 THE DIATOMACE4: OF PHILADELPHIA AND VICINITY PINNULARIA VIRIDIS NITZSCH Valve linear-elliptical, with rounded ends; axial area narrow, widened in the middle; strize, 6 to 7 in 10 yn, crossed by a band as wide as one-third the length of the striae. Common in fresh water. Pl. 29, Fig. 2. Quite variable in size. Approaches P. major by intermediate forms as in Fig. 9, Pl. 29. PINNULARIA VIRIDIS VAR. FALLAX CL. Valve linear, with rounded ends; axial area narrow, slightly widened in the middle; striz sometimes unilaterally interrupted, nearly parallel, 10 in 10 y. Eln, N. J. Pl. 29, Fig. 4. In Fig. 2, Pl. 30, a form is represented which corresponds closely to Navicula viridis var. B, of Wm. Smith. It is given as synonymous with var. fallax; it is bilaterally inter- rupted. Blue clay. PINNULARIA VIRIDIS VAR. ? Valve linear-elliptical, with rounded ends; axial area narrow, widened in the middle to a transverse fascia which is sometimes unilateral; strie, 14, in the middle, divergent, convergent at the ends and closer, crossed by a narrow band. L. 45-60 u. Fascia some- times absent or very narrow. Northbrook, Pa. Pl. 30, Fig. 17 (represents a form with wider area than usual). PINNULARIA VIRIDIS VAR. CAUDATA N. VAR. Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, widened to an orbicular space in the middle; striz radiate in the middle, 11-12 in 10 u, convergent and’ closer at the ends, crossed by a narrow band; median line with very long terminal fissures; terminal nodules noticeable because of the thickening of the edges of the terminal striz. L. 43 p. Fresh water, Newtown Square. Not common. Pl. 30, Fig. 18. PINNULARIA SOCIALIS (PALMER) Valve linear, with rounded ends; axial area broad, one-third the width of the valve; strie slightly radiate in the middle, convergent at the ends, elsewhere parallel, 8 in 10 y, crossed by an indistinct band about one-third the length of the strie. L. 60-120 u. This species, discovered by Mr. Palmer near Media, Pa., is remarkable for the group- ing of the frustules ‘‘held with girdle sides together by a siliceous cementing of valve edges and enclosed in a common coleoderm.’’ The usual number included in a group is four, but sometimes six or eight are noticed. The frustules adhere near their ends and are so firmly fastened that boiling in nitric acid and bichromnate of potash for fifteen minutes will not separate them. Navicula socialis Palmer (Proc. Acad. Nat. Sci., Phila., 1910, p. 460, Pl. 35). Media, Pa. Pl. 29, Fig. 5. THE DIATOMACE.Z OF PHILADELPHIA AND VICINITY 105 PINNULARIA ZSTUARII CL. Valve linear, with rounded ends; axial area broad, less than one-third the width of the valve; central area a transverse fascia; strie, 7in 10 u, parallel except at the ends where they are slightly convergent; median line flexuose, with short, terminal semicircular fis- sures. L. 85 HL. Port Penn, Delaware River. Rare. Pl. 29, Fig. 6. GRACILLIME PINNULARIA MOLARIS (GRUN.) CL. Voive very convex, linear, with sub-cuneate ends; axial area narrow, expanded in the middle to a transverse fascia reaching the margin; strie divergent in the middle, con- vergent at the ends, 16in10u. L. 60 un. Fresh water. Pl. 29, Fig. 15. PINNULARIA LEPTOSOMA GRUN. Valve linear, rounded at the ends; axial area narrow; central area a broad transverse fascia; strie slightly divergent in the middle and convergent at the ends, 17 in 10 u in the middle, closer at the ends. L. 56 pu. Fresh water. Not common. Pl. 30, Fig. 10. CaPITATE PINNULARIA MESOLEPTA EHR. Valve linear, with triundulate margins and capitate ends; axial area narrow, widened in the middle; stria divergent in the middle, convergent at the ends, about 12in10y. L. 34 yp. Common in fresh water. Pl. 29, Fig. 13. PINNULARIA MESOLEPTA VAR. STAURONEIFORMIS GRUN. Valve triundulate, capitate; axial area narrow, widened in the middle to a transverse fascia, broader at the margin; strie strongly divergent in the middle and convergent at the ends, 9-10 in 10 u. L.70y.— Pavonia, N. J., artesian well. Fresh water. Pl. 30, Fig. 20. PINNULARIA SUBCAPITATA GREG. Valve linear or linear-elliptical, with sub-capitate ends; axial area distinct, widened to a transverse fascia in the middle; strie divergent in the middle, convergent at the ends, 13in10y. L. 32 up. Fresh water. Pl. 29, Fig. 20. 106 THE DIATOMACE OF PHILADELPHIA AND VICINITY PINNULARIA SUBCAPITATA VAR. PAUCISTRIATA GRUN. Valve linear-elliptical, with rounded ends; axial area gradually widened into a broad, transverse fascia; stris divergent in the middle, convergent at the ends, 11-12 in 10 u. L. 47 py. Fresh water. Pl. 30, Fig. 16. PINNULARIA TERMES (EHR.) A. S. Valve linear, with concave margins and rostrate-capitate ends; axia! area narrow, widened in the middle to an orbicular or sub-quadrate space; strie divergent in the middle, scarcely, if at all, convergent at the ends, 10 in 10 u. Pensauken, N. J., artesian well. Pl. 29, Fig. 17. This is, I believe, the form figured by Schmidt (Atlas, Pl. 45, Fig. 67). Cleve refers it to Pinnularia interrupta forma biceps, in which the central .pace is rhomboid. PINNULARIA TERMES VAR. STAURONEIFORMIS V. H. Valve linear, with concave margins and capitiate-rostrate ends; axial area narrow, widened into a rhomboidal fascia, reaching the margin; striz, 10 in 10 y, divergent in the middle, convergent at the ends. Pinnularia interrupta forma stauroneiformis Cl. Fresh water. Pl. 29, Fig. 14. PINNULARIA APPENDICULATA (AG.) CL. Valve linear, with subcapitate ends; axial area narrow; central area a transverse fascia; stric divergent in the middle, convergent at the ends, 16in10y. L. 43 u. Fresh water. Marl pits, Lenola, N. J. (Palmer). Pl. 29, Fig. 18. PINNULARIA BRAUNII GRUN. Valve linear-lanceolate, with capitate ends; axial area gradually widened toward the middle and expanded into a fascia reaching the margin; strie divergent in the middle, con- vergent at the ends, ll in10y. L. 52 p. Pensauken, N. J., artesian well. is SS Pl. 29, Fig. 16. PINNULARIA MICROSTAURON (EHR.) CL. Valve convex, linear, tapering to sub-cuneate or sub-rostrate ends; axial area very narrow; central area a broad fascia; strive divergent in the middle, convergent at the ends, 12in10y. L. 35h. Pavonia, N. J., artesian well. Pl. 29, Fig. 19. This form does not exactly correspond to Cleve’s diagnosis, as the ends are not broad. All species in the group Capitate are quite variable. THE DIATOMACE-E OF PHILADELPHIA AND VICINITY 107 DIVERGENTES PINNULARIA DIVERGENS VAR. ELLIPTICA GRUN. Valve linear, with rounded ends; axial area widened in the middle to a transverse fascia; striz, 9 in 10 y, divergent in the middle, convergent at the ends. I.. 150 u. Fresh water. Not common in this locality. Pl. 31, Fig. 13. PINNULARIA CARDINALICULUS CL. Valve linear, with rounded ends; axial area wide, less than one-third the width of the valve, expanded to a transverse fascia; striw divergent in the middle and slightly conver- gent at the ends, 9in10 yu. L. 97 x. Blue clay. Pl. 30, Fig. 1. As a rule, the median fissures in Pinnularia are turned inwards on the side of the longer edge of the terminal fissures, but not always. In this specimen the median fissures are turned slightly toward the side of the shorter edge of the terminal fissures. PINNULARIA LEGUMEN EHR. Valve linear, with more or less triundulate margins and broad, capitate ends; axial area less than one-fourth the width of valve, widened in the middle; strix strongly divergent in the middle and convergent at the ends, 10 in 10 yu. L. 84 u. Fresh water. May’s Landing, N. J. Pl. 30, Fig. 3. PINNULARIA LEGUMEN VAR. ? Valve asin type, but with 2 transverse fascia; striz, 10 in 10 », curved or bent near the ends. L. 84 yp. This form is not var. florentina Grun. May’s Landing, N. J. (with the type). Pl. 30, Fig. 4. PINNULARIA BREBISSONII (KUETZ.) CL. Valve linear-elliptical, with rounded ends; axial area narrow, widened into a transverse fascia which is usually broader at the ends; strie divergent in the middle, convergent at the ends, about 12 in 10 nu. L. 40-60 » (CI.). Fresh water. Common. PL 29, Fig. 12; Pl. 31, Fig. 11. Variable in outline. PINNULARIA MORMONORUM (GRUN.) Valve linear, with rounded ends; strie divergent in the middle, convergent at the ends, 10 in 10 y; axial area rhombic-ianceclate, widened to a fascia usually reaching the border. L. 62 p. Navicula-mormonorum Grun. Common near Willistown, Pa. This form is regarded by Cleve as P. brébissonii, but the axial area appears to dis- tinguish it. The valves are sometimes narrowed in the middle. Pl. 29, Fig. 11. 108 THE DIATOMACE OF PHILADELPHIA AND VICINITY BrEvVISTRIATE PINNULARIA ACROSPHERIA (BREB.) CL. Valve linear, gibbous in the middle and at the ends; axial area about half the width of the valve; median line with approximate central pores; median area punctate; strie nearly parallel, radiate at the ends, 9in 10 w. L. 32-180 u (CL). Blue clay. Recent, fresh water. Pl. 30, Fig. 7. PINNULARIA ACROSPHERIA VAR. TURGIDULA GRUN. ? Valve strongly gibbous in the middle; ends rounded; striez, 12-13 in 10». L. 54 x. Blue clay, Gloucester, N. J., artesian well. Pl. 30, Fig. 8. Z PINNULARIA BLANDITA N. SP. Valve linear, gibbous in the middle, and with rounded ends; strie radiate in the middle, convergent at the ends, 13 in 10 y; axial area about one-fourth the width of the valve, widened in the middle; median line with small semicircular terminal fissures. L. 65 p. Pavonia, N. J., artesian well. Rare. Pl. 30, Fig. 25. PINNULARIA PARVA (EHR.) CL. VAR. ? Valve linear, tapering to the subcapitate ends; axial area broad, lanceolate; median line with approximate central pores and semicircular terminal fissures; strie slightly diver- gent in the middle and convergent at the ends, 12in10yu. L. 58 pn. Differs from the type in having finer strie. Atco, N. J. Pl. 30, Fig. 14. PINNULARIA NODOSA FORMA CAPITATA CL. Valve triundulate, with capitate ends; axial area about one-fourth the width of valve; strive parallel, convergent at the ends, 10 in 10 », sometimes interrupted in the middle. L. 47 u. 2 Fresh water. Common. Pi. 30, Figs. 15 and 19. PINNULARIA POLYONCA (BREB.) LEWIS Valve with triundulate margins, more inflated in the middle, with capitate ends; axial area very broad; strie marginal, short, 9 in 10 u, divergent in the middle, convergent at the ends. L. 97 uz. Kirkwood Pond, N. J. Pl. 30, Fig. 21. The description of Kuetzing (Species Algarum, p. 85), where he states that the margins are ‘‘triundulate, the median inflation larger, apices rounded-capitate,”’ appears to suffi- ciently distinguish this species, which I believe to be the same as Brun’s Navicula peripunc- tata, except that the form figured (Espéces Nouvelles, Pl. 16, Fig. 11) is interrupted in the middle, a-common variation in these forms. Cleve makes Navicula polyonca Bréb. equal Pinnularia mesolepta, but at the same time he considers Lewis’ form and also Brun’s as equivalent to Navicula formica Ehr., and calls it Pinnularia nodosa var. formica Ehr. P. mesolepta has a narrower area than nodosa. I adhere to Lewis’ identification, as in any case it is the form here figured and is nearly, if not quite, the same as Brun’s species. THE DIATOMACEE OF PHILADELPHIA AND VICINITY 109 DIstTanTES PINNULARIA LATA (BREB.) WM. SM. Valve linear-elliptical, broad; axial area broad, widened in the middle; stric slightly radiate in the middle, 3 in 10 »; median line oblique, the terminal fissures hook-shaped. L. 86 p. Blue clay. Not uncommon. Pl. 30, Fig. 23. PINNULARIA BOREALIS EHR. Valve linear, with rounded or sub-truncate ends; axial area about one-fourth the width _ of the valve, widened in the middle; median line with large hook-shaped terminal fissures; strie,4or5inl0yp. L. 54 un. Blue clay. Occasional in fresh water in a smaller form. Specimens occur intermcdiate between P. lata and P. borealis. Pl. 30, Fig. 22; Pl. 31, Fig. 12. PINNULARIA BOREALIS VAR. SCALARIS (EHR.) CI. Valve narrow, linear; axial area broad, widened into a transverse fascia; strie, 8 in Wp. L. 32h. Fresh water. Pl. 30, Fig. 24. TABELLARLE PINNULARIA STOMATOPHORA (GRUN.) CL. Valve linear, with rounded ends; axial area less than one-third the width of the valve, gradually widened in the middle to a transverse fascia; on each side of the central nodule is a lunate space; strie divergent in the middle, convergent at the ends, 13 in 10 yu; terminal fissures very long, bayonet shaped. L. 75 u. Cleve describes a variety continua as not interrupted. In some forms the fascia is marked by very faint, short striae on the margin. Fresh water. Newtown Square. Pl. 30, Fig. 12. PINNULARIA GIBBA (KUETZ.) V. H. Valve linear, tapering to the subcapitate ends; axial area dilated in the middle; strie, 10-11 », divergent in the middle, convergent at the ends. L. 80 u. Fresh water. Pl. 30, Fig. 5. : PINNULARIA MESOGONGYLA (EHR.) CL. Valve linear, gibbous in the middle, ends subcapitate; axial area narrow, widened in the middle to a large orbicular space; strie strongly divergent in the middle, convergent at the ends, 11 in 10 yn. L. 60 nu. Fresh water. Common. Pl. 30, Fig. 6. 110 THE DIATOMACE4E OF PHILADELPHIA AND VICINITY PINNULARIA STAUROPTERA (GRUN.) CL. Valve linear, with slightly triundulate margins tapering to the subcapitate ends; axial area more than one-third the width of the valve, slightly widened in the middle; median line with approximate central pores and semicircular terminal fissures; strie divergent in the middle, convergent at the ends, 11 in 104. L. 82 u. May’s Landing, N. J. Pl. 30, Fig. 13. Some of the forms are more triundulate than the specimen figured. PINNULARIA STAUROPTERA VAR. INTERRUPTA CL. Valve linear, tapering to the subcapitate ends; axial area broad, widened in the middle to a transverse fascia; striz divergent in the middle, convergent at the ends, 10 in 10 y; median pores approximate. L. 118 u. Schuylkill River. Pl. 30, Fig. 11. PINNULARIA TABELLARIA (EHR.) CL. Valve linear, gibbous in the middle and tapering to the subcapitate ends; axial area about one-third the width of the valve, widened in the middle; median line with approxi- mate central pores and bayonet-shaped terminal fissures; strize sometimes unilaterally interrupted, divergent in the middle, strongly convergent at the ends, 9in10y. L. 138 yu. Blue clay. Rare. Pl. 30, Fig. 9. The form here figured has coarser strive than in the type which is also usually more capitate. P. legumen has triundulate margins, P. mesogongyla has an orbicular space, while P. gibba has the space widened. According to Cleve, P. gibba has approximate central pores, as has also P. mesogongyla. In what I have considered to be P. legumen, the central pores are more approximate than in the other two species mentioned. In fact, all of the three resemble each other closely, and are variously named by different authors. The form of P. gibba here figured, which may be P. stauroptera, is not the typical form of Wm. Smith, which has a narrow area and central space. There are, however, among the typical speci- mens in H. L. Smith’s Type Slide No. 275, smaller valves which show a resemblance. Marin& PINNULARIA RECTANGULATA (GREG.) CL. Valve linear, with abruptly rounded ends; axial area very narrow; central area large, somewhat quadrate; striz, 7-8 in 10». L. 78 pz. Navicula rectangulata Greg. Shark River, N. J. Pl. 29, Fig. 7. THE DIATOMACE.X OF PHILADELPHIA AND VICINITY 111 EPITHEMIA BREB. (1538) (epithema, a cover or lid) Frustules epiphytic, solitary, sometimes geminate, adherent on the ventral side at the ends; in zone view rectangular, sometimes tumid in the middle. Valve arcuate, having an interior costate stratum or transverse septa extending to the girdle, often detached, and an exterior valve surface with transverse rows of puncta. Central and terminal nodules not easily seen; in some species a true raphe is indicated. The resemblance between Epithemia and Eunotia has been already mentioned. In the shape and striation of the valves there is an approach to Cymbella. The genus is divided into two groups, one in which the cost alternate with double rows of puncta, asin E. turgida, and the other in which the rows of puncta are more than two. The endochrome usually consists of a band lying along the ventral zone and extending in two flaps on the valves. EPITHEMIA TURGIDA (EHR.) KUETZ. Valve arcuate, with ends subcapitate; cost radiate, 4 in 10 u, alternating with double rows of puncta. Median nodule central, the raphe curved toward the ventral edge which it closely follows. Parasitic on alge. Very common in fresh water, especially in ponds. In the figure the valve is asymmetrical with respect to the transverse axis, an unusual condition. Pl. 31, Fig. 14. EPITHEMIA ARGUS KUETZ. Valve with dorsal margin convex, and ventral margin nearly straight; ends rounded, constricted; cost robust, alternating with more than two rows of puncta; zone view rec- tangular, the thickened ends of the cost forming large nodules in a row along the edge of the valve next to the connecting zone. Cystopleura argus (Ehr.) Kunze. Common in fresh water. Pl. 31, Figs. 15 and 21. EPITHEMIA ARGUS VAR. ? Valve strongly arcuate on the dorsal side and concave on the ventral; tapering to the rounded but not produced ends; cost at unequal distances, about 2 in 10 y; granules in transverse rows, 8in10y. L. 100 un. Pensauken, N. J., artesian well. Pl. 31, Fig. 16. EPITHEMIA MUELLERI A. 8. ? fs Valve broad, convex, slightly arcuate, with obtuse, somewhat constricted apices; cost about 4 in 10 u; striz, 12-14 in 10 y; in zone view the outline is rectangular, slightly tumid in the middle. L. 78 u. Blue clay. Pl. 31, Fig. 17. 8 112 THE DIATOMACE.Z OF PHILADELPHIA AND VICINITY EPITHEMIA ZEBRA VAR. PROBOSCIDEA (KUETZ.) GRUN. Valve convex on the dorsal, concave on the ventral side; cost, 3-4 in 10 y, slightly radiating; apices recurved, capitate. Blue clay. Pl. 31, Fig. 18. EPITHEMIA GIBBERULA VAR. PRODUCTA GRUN. Valve narrow, lunate, with produced and arcuate apices; coste radiate, 3-4 in 10 p; striz, 16-18 in 10 », punctate. L. 58 yu, usually smaller. Blue clay. Pl. 31, Fig. 19. EPITHEMIA MUSCULUS KUETZ. Valve short, strongly arcuate on the dorsal, concave on the ventral side; apices slightly produced; cost radiate, about 5 in 10 y; strie, 15 in 10 », punctate. L. 20-60 uz. Shark River, N. J. Pl. 31, Fig. 20. EPITHEMIA MUSCULUS VAR. CONSTRICTA (BREB.) V. H. Frustule elliptical, slightly constricted in the middle. Valve convex on the dorsal, straight on the ventral side; coste about 4 in 10 y; sti about 18 in 10 y, finely punctate. L. 45 p. Epithemia succinta Bréb. New Rochelle, N. Y. ae Pl. 31, Fig. 22. RHOPALODIA MUELLER (1885) (Rhopalodes, like a war club) Frustule in zone view linear, linear-elliptical (in our species), or clavate. Valve reni- form or lunate; a raphe, not visible in some species in the usual position of the valve, is found along the convex edge or keel. Median and terminal nodules, although very small, can be determined. The name is more appropriate to the African species which are clavate. Two species only are found in this locality. The chief distinction between Epithemia and Rhopalodia is in the position of the raphe and the nodules. In R. gibba and R. ventricosa the coste are parallel and not radiate since the valves are not iunate. = Chromatophore a single band irregularly divided. RHOPALODIA GIBBA (KUETZ.) MUELLER Valve linear, arcuate on the dorsal, straight on the ventral side, reflexed at the extrem- ities. Coste, 6-7 in 10 y; strie about 14in 10». L. 80-200 p. Fresh water. Common. Pl. 31, Fig. 23. In this species the raphe and nodules can be seen only when the valve is examined at right angles to its usual position. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 113 RHOPALODIA VENTRICOSA (KUETZ.) MUELLER Valve gibbous in the middle on the dorsal side, straight on the ventral side, with reflexed apices; coste, 7 in 10 y; strie, 14-16 in 10 up. L. 40-100 z. The median nodule appears as a minute depression in the middle of the dorsal side. The two species usually occur together. ‘ Epithemia gibba var. ventricosa Kuetz. Pl. 31, Fig. 24. SURIRELLOIDE The Surirelloidex are usually understood to include the genera Surirella, Podocystis, Cymatopleura and Campylodiscus, all of which resemble each other more or less, either in having a keel or markings like the divisions of the keel in Surirella and a median line, or pseudoraphe. The genus Nitzschia also has a keel, but it does not border each side of the valve as in Surirella, being found either near one margin or between it and the centre. Certain of the Surirelle are allied to the group Tryblionella of the Nitzschie, while forms of Stenopterobia are distinguished with difficulty from the group Sigmata. The following arrangement, therefore, is intended to include all genera having a keel or something which resembles it. Hantzschia.—Valve asymmetrical; keels of the two valves opposite each other. Nitzschia.—Valve asymmetrical; keels not (usually) opposite each other. Surirella.—Valve usually symmetrical; a keel on each border. Cymatopleura.—Valve without an elevated keel, but with markings like those of Suri- rella; undulated in zone view. Campylodiscus.—Valves saddle-shaped. HANTZSCHLA GRUN. (1877) (named after C. A. Hantzsch) Valve arcuate, with rustrate ends; keel puncta short, prolonged into cost or extend- ing across the valve; median nodule rudimentary; the keels of the two valves opposite each other. Distinguished from Nitzschia chiefly by the position of the keels. According to Mereschkowsky, however, two species of Nitzschia, N. lanceolata and N. spectabilis, show the same peculiarity. Chromatophores four, two on each of the zones (Mereschkowsky). ~ HANTZSCHIA AMPHIOXYS (EHR.) GRUN Valve slightly arcuate, with rostrate apices; keel puncta, 8 i in-10 yu; striz transverse, 16-18 in 10 p, punctate. L. 60 uy. . 7 Quite variable. Fresh water. Pl. 32, Fig. 9. 114 THE DIATOMACE OF PHILADELPHIA AND VICINITY HANTZSCHIA AMPHIOXYS VAR. MAJOR GRUN. Valve as in type, but the keel puncta are 5 in 10 » and the striw are 11-12 in 10 uz. L. 71 p. H. amphioxys var. major Grun. is stated to be 120 » in length. The present form is smaller but corresponds in puncta and striation. Van Heurck remarks that it approaches H. virgata. Abundant in sand ripples on the beach at Cape May, N. J. Pl. 39, Fig. 4. Fig. 6, Pl. 39, is drawn from an authentic specimen of Wm. Smith’s Nitzschia amphi- oxys, from England, and is introduced for comparison. The central nodule is not evident. Fig. 3, Pl. 39, is from a specimen from an unknown locality. The keel puncta are 6 and the striz 16 in 10 y. HANTZSCHIA VIRGATA (ROPER) GRUN. Valve arcuate on the dorsal side, nearly straight on the ventral side, with rostrate, recurved apices; keel puncta prolonged to one-third the width of the valve, 4 in 10 yu; trans- verse strie, 9-10 in 10y. L. 115 nu. Shark River, N. J. (Kain). I have not been able to find this form on our coast. The figure is drawn from a speci- men from another locality. Pl, 32, Fig. 23. HANTZSCHIA MARINA (DONK.) GRUN. Valve with dorsal margin slightly arcuate, ventral margin straight; apices rostrate and recurved; keel puncta, 6 in 10 », prolonged into coste across the entire valve; trans- verse strice, 12 in 10 yu, in double rows of alternating puncta between the coste. L. 106 u. Epithemia marina Donkin. Along the coast. Pl. 32, Fig. 22. - NITZSCHIA HASSALL (1845), em. GRUN. (1880) (named after Christian L. Nitzsch, of Halle) Frustules usually free, sometimes enclosed in tubes or united into a filament. Valves keeled, the keels of the two valves usually diagonally opposite (see Hantzschia) ; keel puncta short or prolonged. According to Mereschkowsky, there are at least two endochrome plates placed trans- versely on the zones; sometimes there are from four to six plates, in one species twen.y granules and in another no trace of any endochrome whatever. The following analysis is that of Grunow as given in Cleve and Grunow’s “ Arctic Diatoms,” and adopted and illustrated by Van Heurck in his ‘‘Synopsis.” GROUPS 1. Tryblionella—Keel very excentric, valve often folded; keel puncta indistinct, usually the same in number as the strie. 2. Panduriformes.—Valve broad, constricted in the middle, with more or less evident fold; keel very near the edge; keel puncta quite evident or apparently wanting. THE DIATOMACE-E OF PHILADELPHIA AND VICINITY 115 3. Apiculute.—Keel very near the edge; valve linear or somewhat narrower in the middle; strie on the lougitudinal fold fainter than on the remaining surface, or wanting; puncta not in quincunx. 4. Pseudo-Tryblionella—Keel more or less close to the edge; valve with a more or less deep longitudinal fold over which the strix are spread in the same way as over the remain- ing surface; keel puncta always distinct. 5. Circumsute.—Valve with more or less wide longitudinal fold; keel very excentric; keel puncta quite evident; surface of valve irregularly punctate and also traversed by rows of delicate puncta which belong to a different layer of the valve. 6. Dubie.—Like the group Pseudo-Tryblionella, but the valves are not so much folded; frustules sometimes narrowed in the middle. The separation of species is difficult and, in part, doubtful. Keel excentric. -7. Bilobate.—Like the group Dubie, but with more central keel and so forming a transition to the group Pseudo-Amphiprora; valves without longitudinal folds. 8. Pseudo-Amphiprora.—Valve with quite central, sharp keel, arcuate, without longi- tudinal fold; keel puncta always evident; frustule narrowed in the middle with more or less marked central nodule. Includes two species not found in this locality. 9. Perrya.—Valve arched with very sharp central keel; not narrowed in the middle; keel puncta mostly on short or long lines which are sometimes interrupted. Includes six species not found in this locality. 10. Epithemioidee.—Keel excentric; keel puncta extended into coste across the entire valve. 11. Grunowia.—As in the group Epithemioidex, except that the coste are shorter, not extending across the valve; keel very excentric. 12. Scalares.—Like Grunowia, but with sharper, somewhat excentric keel; transverse section of frustule quadrangular. 13. Insignes.—Like Scalares, but with more central keel so that many of the forms are near the group Perrya; frustule somewhat sigmoid. 14. Bacitlaria.—Keel central or nearly so; valve somewhat arched; keel sharp, as in the group Insignes. 15. Vivaces.—Keel moderately excentric; valve, according to position, semi-lanccolate, with keel puncta in short rows, or lanceolate with quite central keel. The valves have in many positions a resemblance to Hantzschia, so that N. vivax frequently becomes con- founded with a form of H. amphioxys. The median keel puncta are not distant and a central nodule is not evident as is the case in all species of Hantzschia. 16. Spathulate.—Like the group Bacillaria, but usually with very delicate striated valves; keel in valve view usually bordered with two parallel lines. 17. Dissipate.—Like Vivaces and Spathulate, but with smaller central keel and without parallel lines. Valves usually small, very delicately striated; no central nodule. 18. Sigmoidee.—Keel quite central; no parallel lines; frustule sigmoid; valve without longitudinal furrow; keel puncta not extended; no central nodule evident. 19. Sigmata.—Like Sigmoidex, but with a more excentric keel. 20. Obtuse.—Like Sigmata, with a more or less excentric kee! which has in the middle a small bending to the inside; middle keel puncta somewhat more distant than the others, and between them a central nodule evident. 116 THE DIATOMACE OF PHILADELPHIA AND VICINITY 21. Spectabiles—Valve large, slightly arcuate, with excentric keel; no longitudinal folds; keel puncta somewhat extended over the valve but much less than in the group Insignes, and often scarcely perceptible. 22. Lineares.—Keel somewhat excentric, but less than in Spectabiles; frustule straight, sometimes a little constricted in the middle, so that a transition is shown to the groups Dubiz and Bilobate. Valve without longitudinal fold; keel puncta round or somewhat angular, scarcely extended. 23. Lanceolate.—Valve lanceolate, linear-lanceolate or rarely elliptical, with very excentric keel; not folded; keel puncta not extended. 24. Nitzschiella.—Valve with excentric keel and long, produced apices. TRYBLIONELLA NITZSCHIA TRYBLIONELLA HANTZSCH Valve elliptical-lanceoiate, with subacute apices; longitudinal fold well marked; striz coarse, transverse, 5 in 10 »; indistinct puncta intermediate between the striea. L. 45 un. Quite variable. Blue clay. Pl. 32, Fig. 8. NITZSCHIA GRANULATA GRUN. Valve elliptical or elliptical-lanceolate; strie in double rows, each row of three or four small puncta along the margin and rows of large puncta about 6 in 10 » across the valve. L. 28-44 pu. Blue clay. Along the coast. Pl. 32, Fig. 3. NITZSCHIA NAVICULARIS (BREB.) GRUN. Valve elliptical-lanceolate, with acute apices; strie on one side a double row of large and small puncta, and on the other side radiate shert rows of large puncta, 7 in 10 yp; middle of valve hyaline. L. 35-60 zu. ; Blue clay. Not common. ‘ Pl. 32, Fig. 4. NITZSCHIA COMPRESSA (BAIL.) Valve elliptical-lanceolate, sometimes acuminate; striz, 6 or 7 in 10 yu, coarsely punctate. L. 56 u. Pyzidicula compressa Bailey. Nitzschia punctata (Wm. Sm.) Grun. Tryblionella punctata Wm. Sm. Common along the coast. Pl. 39, Fig. 7. Var. minor (H. L. Smith).—Valve acuminate; striz, 8in 10 yu. L. 22 u. Pyzxidicula compressa var. minor H. L. Smith, Type Slide No. 431. Pl. 39, Fig. 8. The smaller forms occur northward, while the larger are found southward. This is unquestionably Bailey’s form, as indicated by his figure and by the fact that it is found everywhere along the coast. Wm. Smith’s T. punctata is the same species, although the puncta are smaller. THE DIATOMACE.Z OF PHILADELPHIA AND VICINITY 17 PANDURIFORMES NITZSCHIA PANDURIFORMIS GREG. Valve elliptical, constricted in the middle, with sub-cuneate apices; longitudinal fold, with a punctate longitudinal line; strie transverse and oblique, 15 in 10 4; keel puncta, 6 in10u. L. 108 z. Along the coast. More often found southward. Pl. 39, Fig. 2. NITZSCHIA PANDURIFORMIS VAR. MINOR GRUN. Valve elliptical, constricted in the middle, with cuneate apices; keel puncta, 9 in 10 pj striz in transverse and ublique lines about 20 in 10 yu; longitudinal fold bordered by a punctate lire. L. 34 x. Pavonia, N. J., artesian well. Pl. 32, Fig. 5. The var. continua Grun. is reported as occurring in Shark River. It varies in having the longitudinal fold punctate. It is also usually smaller than var. minor. APICULATE NITZSCHIA APICULATA (GREG.) GRUN. Valve oblong-linear, with cuneate-apiculate apices; striae punctate, apparently inter- rupted or pervious, about 18in10y. L. 26 u. Chester River, Md. Pl. 32, Fig. 6. The puncta are continued across the valve, but are less distinct on the fold. The figure shows the entire frustule with the fold on each valve. The valves are sometimes slightly constricted. NITZSCHTA ACUMINATA (WM. SM.) GRUN. Valve linear, sometimes slightly constricted in the middle, with acuminate apices; longitudinal fold entirely without or with indistinct strix; keel puncta not evident; striz, 14-15 in 104. L. 82 up. Port Penn, Delaware River. Pl. 32, Fig. 13. NITZSCHIA PLANA WM. SM. Valve linear; apices acute, slightly constricted in the middle; longitudinal fold further from the keel than the margin, broad, with scattered puncta; strix subtle, irregular, inter- rupted, about 18 in 10 u; keel puncta oblong, 3-6 in 10 4. L. 100-170 xz. Blue clay. Along the coast. Pl. 32 Fig. 2. 118 THE DIATOMACE OF PHILADELPHIA AND VICINITY PsEuDO-TRYBLIONELLA NITZSCHIA LITORALIS VAR. DELAWARENSIS GRUN. Valve linear, with obtusely rounded cuneate ends, scarcely, if at all, constricted in the middle; longitudinal fold wide; keel puncta, 5 or 6 in 10 yu, sometimes confluent; strie ob- scure, about 21 in 10 yp. L. 75 un. Delaware River. Pl. 32, Fig. 12. This form is drawn from a slide of Christian Febiger containing an abundance of speci- mens from Delaware City, and marked ‘‘Nitzschia dubia.” CrrcumsuTz NITZSCHIA CIRCUMSUTA (BAIL.) GRUN. Valve elliptical, sometimes more than 200 u in length; longitudinal fold more or less conspicuous; keel puncta about 4 in 10 y», the middle distant with the appearance of a nodule; striz irregular, subtle, finely punctate, frequently interrupted. Sur‘rella circumsuta Bail. Tryblionella scutellum Wm. Sm. Common in brackish water. Pl. 32, Fig. 1. Dusiz NITZSCHIA DUBIA WM. SM. Valve linear, scarcely, if at all, constricted in the middle, with cuneate, produced, apiculate apices, somewhat recurved; keel very excentric; puncta sometimes partly pro- longed, about 9 in 10 y; strie, 20-24 in 10 yu. L. 93 nu. Reported from along the New Jersey coast. Ihavenotseenit. It is generally regarded as fresh-water. Slides sometimes labelled N. dubia are in reality N. litoralis var. dela- warensis. Pl. 39, Fig. 5. 5 The figure is drawn from a specimen from another locality. BiLospaTz NITZSCHIA BILOBATA WM. SM. Valve linear-lanceolate, constricted in the middle, apiculate at the ends; keel puncta 6 in 10 yn, prolonged unequally across part of the valve, the two median sub-remote; strix, 16 in 104. Frustule oblong, truncate, constricted in the middle. L. 120 z. Shark River, N. J., Chester River, Md. Pl. 32, Figs. 10 and 11. EPITHEMIOIDEE NITZSCHIA EPITHEMIOIDES GRUN. ; Valve linear, with cuneate, rostrate apices; slightly constricted on the keel side; keel puncta, 8 or 9 in 10 y, extending as costz across the valve; strie delicate, 22 in 10 uz. L. 47 ug. Brackish water, Long Island Sound. PI. 32, Fig. 21. Ens THE DIATOMACEE OF PHILADELPHIA AND VICINITY 119 GRUNOWIA NITZSCHLA TABELLARIA GRUN. Valve rhomboidal, inflated in the middle; apices produced; keel puncta extend in cost across half of the valve, 7 in 10 y; strie transverse, about 22in10u. L. 20u. Dimerogramma sinuatum Thwaites. Nitzschia sinuata var. tabellaria (Grun.) V. H. Schuylkill River. Not common. Pl. 32, Fig. 7. SCALARES NITZSCHIA SCALARIS (EHR.) WM. SM. : Valve linear, with obtusely conical apices; coste transverse, extending more or less to one-third the width of the valve, 3 or 4 in 10 uy; striz, 9 or 10 in 10 y», punctate. Length of valve quite variable, up to 480 » (Cleve). A well-known form, abundant in salt marshes and more or less brackish water. Pl. 33, Fig. 6. (To the right of the figure is an outline of the valve reduced one-third.) INSIGNES NITZSCHIA INSIGNIS GREG. Valve nearly linear or linear-lanceolate; apices broad, slightly produced, obtuse; keel puncta extended into short coste, 4 or 5 in 10 y; striz about 14 in 10 4. Length variable up to 400 z. Delaware Bay. Pl. 33, Fig. 8. BaciLLaARIA NITZSCHIA PAXILLIFER (0. F. MUELLER) HEIBERG Frustules united in a filament, afterwards free; valve lanceolate with nearly centra! keel; keel puncta, 7-9 in 10 y; strix about 21in10y. L.110x4. Vibrio pazillifer O. F. Mueller. Bacillaria pcradoza Gmelin. Nitzschia paradoza (Gmelin) Grun. Brackish water or streams subject to its influence. Pl. 33, Figs. 13 and 14. Otto Frederick Mueller, in 1786, published at Copenhagen a work on ‘‘Infusorial Ani- malcules,’’ including a description of a Vibrio which he named paxillifer, obviously alluding to the partially-extended frustules bearing at the end a tablet-like bundle. Two years later, Gmelin described the same form as Bacillaria paradoxa, a name still used. Heiberg, however, in 1863, piaced the form under Nitzschia where it properly belongs and called it _ Nitzschia paxillifer (O. F. Mueller). I have adopted Heiberg’s name. Perhaps the most remarkable of all diatoms. ‘Many species possess the power of mo- tion, which, however, is evident only in the free frustule. In N. paxillifer, the movement of the frustules occurs without the loss of continuity or adherence to each other, so that, while at one time the adnate frustules form a narrow filament, like that of Fragilaria, at another 120 THE DIATOMACE OF PHILADELPHIA AND VICINITY time they move laterally to their extreme length and form a thread of frustules adherent at their ends, later resuming their original position. The motion is repeated at intervals of from five to ten seconds. No satisfactory explanation of the movement has ever been made. In the filamentous form the frustules adhere to water-plants. VIVACES NITZSCHIA FLUMINENSIS GRUN. Valve lanceolate, apices produced; keel puncta, 4-6 in 10 yu, partly extended in short coste; stris transverse, 14-15 in 10 », punctate; keel without a pseudo-nodule. L. 73 yu. Common at Greenwich Point, Philadelphia. Pl. 32, Fig. 16. The form here figured is smaller than the type, which is from 130-160 yu in length. SPATHULATE NITZSCHIA SPATHULATA BREB. Frustule linear, truncate, dilated at the ends; zone with longitudinal folds; valve lance- olate, keel central; apices acute, with an elevated appendage; keel puncta, 5-6 in 10 yp; striz very fine. L. 56 u. Atlantic City and Cape May, N. J. (Lewis). Pl. 40, Fig. 3. . DIssIPpaTz ' NITZSCHIA DISSIPATA (KUETZ.) GRUN. Valve lanceolate, with sub-rostrate apices; keel excentric; keel puncta about 6 in 10 p; stric, 14in 10 yu. L. 20-40 uz. Fresh and brackish water. Pl. 40, Fig. 7. SIGMOIDEE NITZSCHIA MACILENTA GREG. Frustule sigmoid, truncate at the ends; valve linear, with sub-acute apices and nearly central keel; keel with 5-6 puncta in 10 y; strie obscure, about 25 to 28 (?)in 104. Length variable, up to 490 pz. As the valve is usually seen when the keel is on the margin, the outline (reduced one- third, shown to the left of the figure) is, as a rule, sigmoid. Delaware Bay. Pl. 33, Fig. 7. NITZSCHIA VERMICULARIS (KUETZ.) HANTZSCH Valve linear, sigmoid, attenuated toward the obtuse ends; keel puncta, 9 in 10 yu, quite distinct; strie very fine. L. 105 p. Fresh-water pools. Pl. 32, Fig. 24; Pl. 33, Fig. 9. THE DIATOMACEE OF PHILADELPHIA AND VICINITY 121 SIGMATA NITZSCHIA SIGMA (KUETZ.) WM. SM. Frustule linear, sigmoid; valve linear, slightly sigmoid, tapering to the sub-acute apices; keel excentric, puncta, 8 in 10 yu; strie, 20-24 in 10 p. L. to 250 u. -Along the coast. Pl. 39, Fig. 13. NITZSCHIA SIGMATELLA GREG. Valve linear, sigmoid, slightly attenuated toward the obtuse apices; keel excentric, puncta, 8-10 (?) in 10 u; strie delicate, 25-30 in 104. L.to 4004. The keel puncta are quite obscure. Nitzschia curvula Wm. Sm. Nitzschia sigma var. curvula (Wm. Sm.) De Toni. Fresh water. Hammonton Pond; May’s Landing, N. J. Pl. 33, Figs. 4 and 5. Gregory remarks that the keel puncta are seen in some specimens. In both of the forms figured I have counted 30 striz in 10 yu, but, after many examinations, I have not been quite certain about the keel puncta. The general appearance of the valves in any position is that of a Stenopterobia or Surirella anceps, with which it occurs. NITZSCHIA CLAUSII HANTZSCH Valve linear, slightly sigmoid, tapering to the sub-capitate ends; keel puncta, 11 in 10 yp; strie subtle. L. 40 u. Abundant in Ridley Creek, Delaware Co. (Palmer). Pl. 32, Fig. 20. Oxstusa NITZSCHIA OBTUSA WM. SM. Frustule sigmoid, rounded at the ends; keel somewhat excentric, inflexed in the middle, the two median puncta distant; keel puncta, 5-6 in 10 uw; striz, 26in 104. L. to 300 p. Along the coast. Pi. 39, Fig. 16. NITZSCHIA OBTUSA VAR. FLEXELLA H. L. SMITH Valve more attenuate at the ends than the type and smaller. Pl. 39, Fig. 14. NITZSCHIA OBTUSA VAR. SCALPELLIFORMIS GRUN. Valve linear, with apices unilaterally truncate; keel excentric; keel puncta, 8 in 10 yu; striz, 26in10u. L. 48 nu. Along the coast. Pl. 32, Fig. 17. 122 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY SPECTABILES NITZSCHIA SPECTABILIS VAR. AMERICANA GRUN. Frustule linear, slightly constricted in the middle, with sub-cuneate ends; valve linear, slightly arcuate, tapering to the sub-rostrate ends; keel excentric, keel puncta sometimes confluent, 4-6 in 10 y, prolonged into short costz; strie distinct, 14 in the middle, 18 at the ends in 10 » (but variable in different specimens). L. 186 u. Blue clay, especially at Tioga St. Pl. 33, Fig. 3; Pl. 39, Fig. 1. This is, probably, one of the most beautiful of the Nitzschia. It sometimes, according to De Toni, reaches a length of 520 x. Grunow states that his variety is found in the S. Bridgeton deposit. In a slide of Meeller labelled “Bridgeton, Maine,” I find specimens identical in every respect with the Philadelphia form. LINEARES NITZSCHIA LINEARIS (AG.) WM. SM. Valve linear, slightly inflexed in the middle; keel excentric; keel puncta, 8-9 in 10 p, the two median distant; striae about 30 in 10 u. Frustules in zone view narrowed toward the ends, truncate. L. 75 u. Very common in fresh water. Pi. 32, Fig. 18. Fig. 20, Pl. 40, a transverse section of frustule. LANCEOLAT NITZSCHIA PALEA (KUETZ.) WM. SM. Valve linear-lanceolate, slightly rostrate at the apices; keel puncta, 10 in 10 yp, the median not distant; stria, 33-36 in 10 u; zone view linear, withroundedends. L. 25-65 p. Fresh water. vl, 32, Fig. 15. fi NITZSCHIA AMPHIBIA GRUN. Valve lanceolate, apices sometimes slightly produced, rounded; keel puncta, 8-9 in 10 y; strie, 16 in 10 py. L. 20-32 y. Fresh water. Pl. 32, Figs. 14 and 25. NITZSCHIA COMMUNIS RAB. Frustule linear, slightly attenuated at the obtuse ends; valve elliptical-lanceolate, attenuated toward the obtuse ends; keel puncta, 12 in 10 y; striae more than 30 in 10 gz. L. 35 pz. Fresh water. Pl. 32, Fig. 19. " NITZSCHIA INTERMEDIA HANTZSCH Valve linear-lanceciate; keel puncta, 8 in 10 yu; strie about 24 in 104. L. 100 n. Crum Creek. Not common. Pl. 33, Fig. 2. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 123 NITZSCHIELLA NITZSCHIA LONGISSIMA (BREB.) RALFS Valve linear-lanceolate, with exceedingly long horns or beaks; keel puncta about 10 in 10 up; strie about 16in 104. L. to 500 xz. Shark River, N. J. Pl. 33, Fig. 1. Forma parva V. H.—Keel puncta, 10-12 in 10 4. L. 70 un. East Park Reservoir, Philadelphia. Pl. 33, Fig. 10. Differs from N. closterium (Ehr.) Wm. Sm. in the keel puncta. The type form occurs in brackish and salt water. The occurrence of the variety in fresh water is another instance of the finding of presumably brackish forms in the water supply of the city. If these cases prove to be unusual, it may be because of one of two rea- sons. The Schuylkill River, before the building of the dam at Fairmount, was tidal as far as the Falls of Schuylkill, and brackish influences, while not now existent, may have caused the growth of forms which now survive. Another reason may be that the opening of the locks at Fairmount Dam may cause a slight admission of brackish forms from tidal water below. The abundance of the brackish species appears to indicate that the first reason is the more plausible. NITZSCHIA REVERSA WM. SM. Valve lanceolate, extended into beaks or horns curving in opposite directions; keel puncta not evident; strie, ‘‘20-26” in 10 ». -L. 70 zu. Brackish water. Abundant in Duck Creek, Delaware River. Pl. 33, Fig. 11. { NITZSCHIA ACICULARIS (KUETZ.) WM. SM. Valve lanceolate, with beaks or horns about half the length of the median part of the valve; keel puncta, 18 in 10 y; strie exceedingly delicate, ‘‘about 40 in 10 u.” L. 45 p. Fresh water. Darby Creek. Pl. 33, Fig. 12. | HOMCOCLADIA AG. (1827) (homoios, like, and clados, a branch) Frustules like Nitzschia, but enclosed in branching or simple tubes. HOMCOCLADIA FILIFORMIS WM. SM. Frustule linear, tumid in the middle, obtuse at the ends; valve linear-lanceclate, with somewhat acute apices; keel central or nearly so; keel puncta, 8 in 10 y; striz delicate. L. 108 p. Fresh and brackish water. Newark, N. J. Pl. 33, Fig. 15. 124 THE DIATOMACE OF PHILADELPHIA AND VICINITY SURIRELLA TURPIN (1828) (named after Dr. Suriray, a. physician of Havre) Valve linear, elliptical or ovate; pseudoraphe linear or lanceolate; a marginal keel forming wings or alz seen in zone view; cost short or reaching the pseudoraphe, frequently with intercostal strise more or less evident. The genus is divided by Grunow according to the length and form of the cost. I include Stenopterobia. Section 1.—Costz of nearly equal width throughout, reaching the pseudoraphe. Section 2.—Costz short or marginal. Section 3.—Coste dilated at the margin, attenuated toward the pseudoraphe. Section 4.—Valve having the appearance of Nitzschia, with inconspicuous ale (Stenopterobia). The endochrome consists of two laminate chromatophores, one on each valve. The auxospores are single, originating from the union of two frustules (H. L. Smith). SECTION 1 SURIRELLA BISERIATA (EHR.) BREB. Valve lanceolate, subacute at the ends; costz robust, about 2 in 10 u, parallel in the middle, radiate at the ends; pseudoraphe narrow. L. 100 zu. Surirella bifrons Ebr. Fresh water. Pl. 39, Fig. 12; Pl. 35, Fig. 2 (smaller form). SURIRELLA LINEARIS WM. SM. Valve linear, with cuneate ends, slightly constricted in the middle; coste parallel, 2-3in 10 yu. L. 90 pu. Fresh water. Pl. 35, Fig. 8. SURIRELLA AMPHIOXYS WM. SM. _ Valve oblong-linear, with cuneate ends; pseudoraphe narrow; costz, 3-4 in 10 y; striz, 14-16 in 10 », somewhat radiate. L. 34-54 p. Surirella melleriana Grun. Fresh and brackish water. Common along the coast. Pl. 35, Figs. 12 and 13. ES ace SURIRELLA ROBUSTA EHR. Valve linear-ovate; pseudoraphe wide; al ‘prominent; cost wide, 114 in 10 uz. Frustule in zone view clavate. L. 200-365 x. Fresh water. Pl. 36, Fig. 2. THE DIATOMACE-E OF PHILADELPHIA AND VICINITY 125 SURIRELLA SPLENDIDA (EHR.) KUETZ. Valve ovate; cost, 113 to 2 in 10 »; pseudoraphe linear, narrow. L. 125-200 pn. Fresh water. Pl. 35, Fig. 3. S. splendida is smaller than S. robusta and wider in proportion, but, as intermediate forms occur, it is difficult to distinguish between them. SURIRELLA ELEGANS EHR. Valve ovate, rounded at one end and acute at the other; pseudoraphe lanceolate, narrow; coste,.114 in 10 yu; strie subtle, 22 in 10 ». Frustule in zene view cuneate. L. 180-220 pu. Fresh water. Pl. 36, Fig. 1. SURIRELLA STRIATULA TURPIN Valve broad, obovate or elliptical, rounded at each end; costa, 114 in 10 p, curved at the ends; striz, 14 in 10 yw. Frustule in zone view cuneate; marginal ale quite robust. L. 100-160 p. Blue clay. Brackish water. Pl. 34, Fig. 1. In the specimen figured, the outline is exactly elliptical, although the species is usually conical at one end. SURIRELLA GEMMA EHR. Valve ovate or ovate-elliptical, rounded at each end, sometimes asymmetrical along the longitudinal axis; pseudoraphe very narrow; coste distant, at irregular intervals, about 2 in 10 », somewhat radiate, reaching the pseudoraphe; striw, 20 in 10 x, punctate. Frustule in zone view cuneate. L. 70-120 un. Along the coast. Pl. 36, Fig. 4. SURIRELLA TENERA GREG. Valve ovate; pseudoraphe narrow, well-defined; cost indistinct, 214 in 10 y, their margins invisible; striz about 14 in 10 u, punctate, more evident near the margin. L. 90 p. Surirella diaphana Bleisch. Pavonia, N. J., artesian well. Pl. 35, Fig. 6. The figure is that of the var. nervosa A. S. (Atlas, Pl. 23, Fig. 15), which differs from the type in having the position of the cost indicated by scattered puncta. 126 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY SECTION 2 SURIRELLA GUATIMALENSIS EHR. Valve ovate; pseudoraphe very narrow and indistinct; coste short, marginal, 2-214 in 10 p, absent from the rounded end. L. 120 up. Surirella cardinalis Kitton. Smith’s Island, Delaware River. Pl. 36, Fig. 5. SURIRELLA OVALIS BREB. Valve ovate; coste short, marginal, radiate, 3-6 in 10 », often unequal; central area ovate, indistinctly costate; striz scarcely visible, about 18 in 10 x; pseudoraphe narrow. L. 45-93 p. Surirella davidsonit A. S. Fresh or brackish water. Pl. 35, Fig. 5; Pl. 39, Fig. 11. The smaller specimen is from the Delaware River, and the larger from the Hudson River. SURIRELLA CRUMENA BREB. Valve nearly orbicular; coste short, marginal, radiate; pseudoraphe narrow, indis- tinct; central area indistinctly costate, sometimes interrupted. On account of the extreme confusion in the names of many forms which appear to be variations of 8. ovalis, I have followed Van Heurck in retaining the original names as specific. De Toni gives S. crumena as a variety of S. ovalis. Fresh and brackish water. Quite common in the Delaware River. Pl. 35, Fig. 4. we - SURIRELLA PINNATA WM. SM. Valve ovate or oblong-ovate; cost reaching the linear pseudoraphe, about 6 in 10 pn. L. 40 u. Surirella ovalis var. pinnata (Wm. Sm.) De Toni. S. pinnata is the type of a number of small forms usually found together, including §S. panduriformis, 8. angusta and S. minuta. Fresh water. Media (Palmer). Pl. 36, Fig. 7; Fig. 9 (abnormal). Var. minuta, a small form of S. pinnata, occurs with the type. SURIRELLA PANDURIFORMIS WM. SM. Valve linear-oblong, with rounded ends, more or less constricted in the middle; other- wise as in S. pinnata. L. 54 u. Fresh water. Pl. 36, Fig. 6. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 127 SURIRELLA ANGUSTA KUETZ. Valve linear, with cuneate ends; otherwise as in 8. pinnata. Fresh water. Pl. 36, Fig. 8. S. pinnata, S. panduriformis, and S. angusta have a narrow centrai area, and differ from S. ovalis which has short costz. SURIRELLA OBLONGA EHR. ? Valve elliptical-lanceolate, with obtuse ends; cost, marginal, 213 in 10 »; median area granulate; pseudoraphe narrow, lanceolate, scarcely visible; strie about 18 in 10 x. L. 60 u. Blue clay. Rare. PL. 35, Fig. 9. This has the outline and appearance of S. oblonga Ehr. (Mik. Pl. 15, Fig. 48), but the cost are closer. SURIRELLA RECEDENS A. S. Valve ovate; costz, 2-214 in 10 u; pseudoraphe narrow, not reaching the ends of the valve; intercostal spaces more evident near the middle. L. 50 uz. Blue clay. Not uncommon. Pl. 35, Fig. 7. SURIRELLA CRUCIATA A. S. Valve ovate; pseudorapke very narrow; costz, 2 in 10 yu; the outline of several of the median costz strongly emphasized, while the other cost are indistinct. L. 54 p. Blue clay. Pl. 35, Fig. 10. SURIRELLA GRACILIS GRUN. Valve linear, with sub-cuneate ends, slightly constricted in the middle; pseudoraphe very narrow; costz, 6-7 in 10 y; transverse strix about 26 in 10 », punctate. L. 75 pz. According to De Toni (p. 598), this form is a Nitzschia. It has, however, a narrow pseudoraphe. Pavonia, N. J., artesian well. Rare. PL 35, Fig. 11. SECTION 3 SURIRELLA FASTUOSA EHR. Valve ovate; costz about 1-2 in 10 y, dilated at the margin and contracting at about one-fourth the distance toward the middle; area, ovate-lanceolate; pseudoraphe, narrow and indistinct; intercostate striz more evident near the margin, 19 in 10 », becoming again evident in a narrow band about one-half the distance to the pseudoraphe. L. 50-120 u. Along the coast. More common southward. Pl. 35, Fig. 1. 9 128 THE DIATOMACEZ OF PHILADELPHIA AND VICINITY SURIRELLA FEBIGERII LEWIS Valve ovate-lanceolate; costze about 21% in 10 » with punctate interspaces extending half the distance toward the median hyaline area, which is divided longitudinally on each side of the narrow pseudoraphe by two longitudinal bands composed of short, transverse, irregular, punctate lines. Along the coast. Pl. 36, Fig. 3. “Section 4 (STENOPTEROBIA) SURIRELLA ANCEPS LEWIS Frustule linear, straight or nearly so; valve sigmoid with rounded apices; coste mar- ginal, nJarly obsolete; strie distinct, about 15 in 10 u; pseudoraphe wide. L. to 320 p. Hammonton Pond and Tom’s River, N. J. Pl. 34, Fig. 2. SURIRELLA INTERMEDIA LEWIS Frustule linear, straight, widened at the truncate ends; valve linear, sigmoid, taper- ing to the sub-acute ends; coste about 5 in 10 yw; strie about 20 in 10 u. L. variable. Hammonton Pond, N. J. Pl. 34, Fig. 3; Pl. 39, Fig. 9 (zone view). This, perhaps, is forma sub-acuta Fricke. Fig. 7, Pl. 34, is probably a small form of 8. intermedia, from Willistown, Pa. It resembles a Nitzschia. Se SURIRELLA DELICATISSIMA LEWIS Frustule linear, rounded at the ends; valve linear-lanceolate, sometimes very slightly constricted in the middle, with acute apices; coste, 5 in 10 y; stria about 20 in 10 pn; pseudo- raphe well defined, lanceolate. L.to90 yp. 3 ~ Fresh water. Newtown Square. Pl. 34, Figs. 5 and 6 (small forms). SURIRELLA ARCTISSIMA A. S. Valve linear, tapering to the sub-acute ends; cost marginal, 5 in 10 »; strie, 18 in 10 y; pseudoraphe not evident. L. 184 p. May’s Landing, N.J.° Pl. 34, Fig. 4. — Fig. 10, Pl. 39, is a small form from Newtown Square, Pa., in which the length is 86 u, the costz 5 and the striz 16 in 10 un. PODOCYSTIS KUETZ. (1844) (pous, a foot, and cystis, a bag) Frustules cuneate, similar to Surirella, but attached by short stipes to other alge; valve obovate. THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 129 PODOCYSTIS ADRIATICA KUETZ. Valve nearly symmetrical, obovate, with transverse cost about 4 in 10 y, alternating with double rows of coarse puncta; median line distinct, linear. L. 43 p. Podocystis americana Bail. Hell Gate, N. Y. Pl. 40, Fig. 6. -CYMATOPLEURA WM. SM. (1851) (cuma, a wave, and pleura, a side) Valve elliptical; surface transversely undulate, with short, marginal costx. Frustule in zone view linear, with undulated sides. Auxospore formation as in Surirella. CYMATOPLEURA SOLEA (BREB.) WM. SM. Valve oblong, with cuneate apices, constricted in the middle; costz about 6 in 10 p; strie, 10 in 10 »; pseudoraphe scarcely visible. L. 50-300 xu. Blue clay. Common in the Hudson River. Pl. 34, Figs. 8 and 9. CYMATOPLEURA ELLIPTICA (BREB.) WM. SM. Valve elliptical; marginal coste short, 3 in 10 u; strix delicate, 18 in 10 »; undulations four or more. L. 70-140 z. Blue clay. Pl. 37, Fig. 1. Forma spiralis.—Valve ovate, swelled into curved ridges at the lower end, with a con- traction of the valve. Port Penn, Delaware River. Pl. 37, Fig. 2. CYMATOPLEURA MARINA LEWIS Frustule linear, with numerous undulations, ends apiculate; valve linear-lanceolate, with acute ends; striz transverse, punctate at unequal intervals, from 16-18 in 10 x. L. 43 yp. East River, N. Y. Pl. 37, Figs. 3 and 4. Lewis states that the ends are more or less truncate. I do not find them so. CAMPYLODISCUS EHR. (1841) (campulos, curved like a saddle) Valve orbicular or sub-orbicular, with coste or punctate rays converging from the circumference toward the hyaline centre, which sometimes appears like a pseudoraphe. Frustule of two saddle-shaped valves at right angles to each other. ‘The zone view may be | of almost any shape according to position. Endochrome consists of two bands, each lining the inner surface of each valve. Auxo- spore and conjugation unknown. 130 THE DIATOMACE® OF PHILADELPHIA AND VICINITY CAMPYLODISCUS ECHENEIS EHR. Valve sub-orbicular, saddle-shaped; cost indistinct, short, marginal; rows of round or elongated puncta converge toward the lanceolate, hyaline median space. Diam. 80- 140 pz. Campylodiscus argus Bail. Blue clay. Reservoir at Thompson and Twenty-sixth Sts., Phila. Pl. 37, Fig. 6. This form, usually considered as brackish and marine, is occasionally found in fresh water. According to Deby, it is fossil in the ‘‘Champlain deposit of N. A.” CAMPYLODISCUS HIBERNICUS EHR. Valve irregularly orbicular; costz, 40-60, about 2 in 10 yu, wide at the margin and attenuated toward the centre which is somewhat quadrate; the radials rough with minute apiculi. Pensauken, N. J., artesian well. Pl. 37, Fig. 5. APPENDIX COLLECTION AND PREPARATION OF DIATOMS It is assumed that every student of the Diatomacee has a general knowledge of the collection, preparation, mounting and examination of material. For the novice, however, the following methods, used by the author for many years, may be of service. Collection of Fresh-water Material—tThe yellow film on the inside of aquaria always contains small species. Stems of water-plants near the shores of ponds and the submerged roots, the brownish coating of rocks in streams and water-falls, fountains, and water-troughs, are prolific. At all times of the year, some diatoms may be found in a thin layer upon the mud of rivers or creeks. In the spring, brown patches of mud, filled with bubbles, floating near the shore in ponds, or coming down with the current in rivers, are rich in various forms. Within the limits assigned to our district, I have made collections in the following locali- ties: Schuylkill River, including the region near Fairmount Dam, several reservoirs and the water-supply; the Wissahickon and Fairmount Park, Darby, Crum and Ridley Creeks, the Neshaminy and the Brandywine; meadow poo!s and rivulets near the city; the upper Delaware, the Water Gap and numerous cascades northward; the Shawangunk Mountains and the Poconos; many parts of New Jersey along the coast; the Pine Barren region, the Hammonton, Atsion and IGrkwood Ponds and the swamps near Atco. In the collection of fresh-water material, it is well to be provided with a number of small bottles. Take a handful of the water-plants or alge, and squeeze the material into the bottles, or, lacking a bottle, wrap it in paper. With asmall forceps it is possible to detach minute quantities of a pure gathering which may not need further preparation be- yond burning to a red heat on the cover-glass before mounting. A malacca cane, with extending rod to which may be screwed a bottle, net, spoon or hook, is useful on a long trip. If it is impossible to separate the thin film of diatoms from the mud in the bed of streams, dip up the surface mud with one bottie, allow to settle a few minutes, then pour off the supernatant liquid, which will be comparatively free from sand, into anvther bottle. It must be confessed, however, that the mud in streams near Philadelphia contains a large quantity of fine mica which, in some instances, it is impossible to remove. Collection of Marine Material—Shell scrapings, the stomachs of fish, marine alge, especially the brown and red alge, the hulls of vessels, mud from anchors and dredgings, are all sources which may prove valuable. In the sand ripples, after the tide recedes, a yellowish-brown deposit will be noticed. This should be taken up carefully with a spoon and placed in a bottle; the sand wil! settle at once and a very pure gathering will be held in suspension in the water. Such collections may be made along the entire coast of New Jersey on sunny days in summer. In salt meadows near Absecon and Hackensack, large quantities of diatoms, including Pleurosigma, may be obtained in the yellow scum floating on the surface. ‘ The Blue Clay Deposit—The blue clay occurs as a pre- or post-glacial deposit in the bed of the ancient Delaware River, and, at depths varying usually from fifteen to forty feet below the surface, has been obtained from artesian wells at Pavonia, Pensauken and Gloucester, N. J., also at Port Penn on the Delaware, and especially from the dredgings ‘ 131 132 APPENDIX made by the removal of Smith’s Island opposite the city. In the city proper, it may be stated briefly that material may be found in a stratum of very light blue clay at a depth varying from twenty to sixty feet in many places south of Arch St. east of Broad St., and also along the beds of ancient rivulets near Tioga St., at Sixteenth St., and in certain other places which were probably subject to tidal overflow. One of the best collections was made along the bank of the Schuylkill at the east end of Walnut St. Bridge, at a depth of thirteen feet below the surface. Excavations for the Reading Terminal and the Subway and several buildings, as the Bingham House, have furnished numerous specimens. Cleaning the Material.—Some gatherings may be so pure as to be ready for mounting when treated with dilute alcohol and oil of cloves. If, when gathered, the diatoms are immersed in a saturated solution of picric acid for several days, they may be stained with carmine or methylene blue, or whatever may be required to emphasize the contents of the frustules, including the endochrome and the pyrenoids. After staining, pass as rapidly as expedient through the treatment with dilute alcohol and oil of cloves, and mount in benzol balsam, avoiding heat. A hot solution of mercuric bichloride is sometimes used for the preservation of the endochrome, although washing is needed before mounting. For the particular stain considered best for certain details of structure, it will be advisable to con- sult works on Micro-Chemistry or Heinzerling (I. c.). The stains of most importance are carmine, metbylene blue, hematoxylin, gold chioride and Bismarck brown. Whatever method may be used in staining, the identification of forms is impossible, in most cases, unless the valves are carefully cleaned and the cell-contents destroyed. For this purpose provide a casserole holding from five to eight ounces, an iron tripod stand with alcohol lamp, several six-inch test-tubes, preferably those with a standard base, fitted with pure rubber corks. Take the material as free from twigs, dead leaves, sand, and other matter as possible, place it in the casserole, and add about the same quantity of nitric acid. Boil for twenty minutes and then add about half a teaspoonful of powdered bichromate of potash, stirring with a glass rod. Then take a beaker-glass partly filled with water and pour into it slowly the liquid which has been allowed to cool a short time, whirling the casserole to cause the concentration of sand in the centre. Allow the material to settle for half an hour or longer, according to the amount of diatoms and their size. Pour off the water, add more water, and place in a test-tube. Repeat the decantation, shaking the test-tube, closed with a rubber cork, vigorously each time. From time to time whirl the diatoms in the casserole and throw away the sand collected in the centre. By repeating the decanta- tion, shaking and whirling, the deposit will be found to consist almost entirely of diatoms. It may be necessary to repeat the boiling in the acid and bichromate. If, however, any detritus other than sand is noted, boil in sulphuric acid and add from time to time minute pinches of powdered chlorate of potash, being careful to protect the eyes by holding a piece of glass before them; otherwise the explosions which occur are likely to throw some of the boiling acid into the eyes and destroy the sight. The material, when clean, should be white or, in the case of Synedra, yellowish. It is quite easy to construct a box fitted with the proper apparatus for boiling and provided with a glass door for observation, and a method of introducing the chlorate of potash through a small aperture or tube. The box may be placed in the garden or fastened outside of a window so that the poisonous fumes may be carried off. An excellent method, in the case of larger forms, is to boil the material already cleaned by the acid in water to which a few shavings of coarse brown soap are added. The differ- ence in density will hold in suspension any flocculent matter, and while many of the smaller APPENDIX 133 forms will not settle, the others will be perfectly cleaned. When satisfied with the cleaning, preserve the stock material in part alcohol and, in using, pour inte a smaller bottle the amount required, replace tne dilute alcohol with distilled water, and mount as directed. It often happens that gatherings are made consisting almost entirely of sand. Attempts at cleaning in the usual way will cause the loss of nearly all of the diatoms. In this case, after the material has been treated with acid until nothing remains but sand and a few diatoms, the mechanical finger must be used. In the cleaning of marine deposits, various methods may be required. In the case of partly siliceous species, washing in pure water repeatedly is all that can be done. The larger and heavier diatoms may be separated from the sand by elutriation or by whirling in a casserole, by rocking in a shallow dish the shape of a watch crystal, or by pouring slowly over a strip of plate-glass at least two feet in length inclined at an angle of thirty degrees. The sand will cling to the glass, while the greater portion of the diatoms will run off. Where particles of shells or foraminifera are present, a preliminary boiling in hydrochloric acid is advisable. In all marine gatherings, the salt should first be washed out before proceeding with the cleaning. For hardened masses of clay and for fossil deposits, it is necessary to boil in carbonate of soda and follow with the acid treatment. Citric acid and acetate of potash used alter- nately in boiling may be tried. Soaking for a time in acetate of potash and allowing the material to deliquesce for a week before further process, has proved successful in some instances. The repetition of several methods and the gentle breaking of the harder masses with the point of a needle will disintegrate almost any diatomaceous earth, but, as a last resort for refractory deposits, boil in pure water, add a piece of caustic potash about the size of a pea, continue the boiling not more than thirty seconds longer, and pour instantly into dilute hydrochloric acid; otherwise the diatoms will be destroyed. Afterwards proceed with the usual treatment. Slides and Covers—Take half an ounce of No. 1 covers, circles, and place them in a wide-mouthed bottle. Add a portion of the following mixture (Dr. Carl Seiler’s formula): Bichromate of potash..... 2.2... cece ccc eee cece tee eens 2 oz. SUS MIFIC HC. ¢.000..ne andre wan Reedodsut hoeuaaian ron sas Coe 3 fl. oz. IW AEE ese ea eeG Detbins ee eee awk bag wae ee eas Sew eee eee 25 fl. oz Shake the bottle in order that the surfaces of the covers may be fully exposed to the action of tine acid, and set aside for several hours. Decant the solution, add water repeat- edly until all traces of the mixture are removed, and keep the circles in the bottle in fifty- per cent. alcohol. When needed, take out a circle with forceps and dry on a linen cloth. The slides may be treated in the same way, or they may be easily prepared by immer- sion in a solution of washing soda, and then washed and dried. This process may be used in cleaning the balsam or styrax from old slides. Preparation of Strewn Mounts.—Place several covers on the mounting stand. With a dipping tube, cover each circle with distilled water, and add a small drop of the prepared diatoms, being careful to avoid any vibration of the stand. Heat the stand until small bubbles begin to appear, remove the lamp, and allow the water to evaporate. If the above method is carefully followed, the diatoms will be deposited in an even layer, provided the material is not too dense. Take a slide, centre it, and place a small amount of styrax on the centre. Invert the prepared cover, and gently place it upon the styrax. Heat the slide 134 APPENDIX on the mounting stard untii the styrax bubbles and then allow to cool. If bubbles still remain, heat again until they disappear. It is well to mount several slides more than required, as some may be imperfect. Preparation of Selected Mounts.—Take a slide, place a minute quantity of beeswax on two places at a distance apart nearly equal to the diameter of the cover used. Place a cover on the wax and press it down flat, or sufficiently to keep it in position. Dip a fine needle into the following cement: Glacial acetic acid... 0. ce ec cee cee cee eee cee nens 12 drachms GORING 5-0 coon Gant hed Pesiagtesyebe tye Re laet RiGee ies 2 drachms PAN COHO] 5 Bate shoe ster hons olsen ch ose ecliaccaniere bce anak era ce de rama 1 drachm This is made by adding the acid to the gelatine in a water-bath and then the alcohol, and filtering. Apply the moistened n¢edle to the centre of the cover and spread as small a quantity as possible in a thin layer. Now place the slide upon the turn table, centre it with respect to the position of the gelatine, and with the finest sable brush draw a circle about a tenth of an inch in diameter around the gelatine in water-color (Windsor), blue or vermilion, or in India ink. Instead of the water-color, a circle of tin-foil the size of the cover and pierced with a hele in the centre may be used, but the colored circle is to be pre- ferred, as, when brought into view, it indicates exactly the focus required for observing the diatom. The bottle containing the cleaned material, which has been kept in water and alcohol, should be refilled with distilled water and well shaken, when a smal! portion may be taken up with a dipping tube and evenly distributed over a portion of a slide and then dried. By the use of a mechanical finger, fitted with a small piece of finely spun glass attached by wax to the holder of the finger, when the microscope is focussed until the glass thread touches the diatom selected, it will adhere to the thread. Raise the body of the micro- scope, remove the slide containing the spread material, or move it to another part of the stage, and place the slide with the prepared cover in the same position. Now carefully lower the body-tube of the instrument until the diatom rests upon the gelatine, breathe gently upon it, remove the cover from the slide, invert it over another slide containing a drop of styrax and proceed by heating to mount as before. The size of the diatom, the amount of gelatine, and severa! other factors, will enter into the question of success or failure. I have, however, employed the above method and have mounted thousands of slides of selected diatoms successfully. It is necessary to avoid any air current which will cause the diatom to fall from the thread. On very cold days the glass thread some- times becomes electrified and the diatoms will not stick; on sultry days in August in our leeality the diatoms will stick too closely. By the same method, slides of arranged diatoms can be made using a glass circle properly marked with lines in the eye-piece. Care should be taken to use glass threads more or less in proportion to the size of the diatoms. A cat’s whisker is preferred by some to the glass thread. It has the advantage of not breaking, but unless it is quite short it is too flexible. If the point of the thread becomes covered with gelatine, lower it into a minute drop of water upon a separate slide, and by moving it about it will be cleaned. The diatom itself may be washed in the same way, if it is not too small. Instruments Required.—For collecting, in order to determine the quality of the find, any simple lens of fifteen to twenty diameters is sufficient. A Stanhope is quite useful APPENDIX 135 although difficult to obtain, while an achromatic triplet of sufficient power will probably be all that is necessary. For selecting with the mechanical finger, an objective of two- thirds-inch focus is the most convenient, but for determining species a one-fifth-inch is needed, an immersion objective being essential for minute forms. No particular form of microscope is required. Any instrument having standard parts, inclination of the body to the axis, 2 sub-stage condenser and movable stage, will prove serviceable in nearly all investigations. For critical work, measurement of strise and location of specimens on the slide, the large models of Bausch and Lomb leave nothing to be desired. One smaller instrument may be used for rapid examination and for selection with the mechanical finger. If the stage is supplied with a vernier, the diatoms can be located rapidly and recorded for future reference. The Zentmayer Army Hospital stand with mechanical stage is excellent. The Continental stands, convenient for laboratory work, especially in the examination of bacteria, are not so serviceable as the larger stands of American and English make. The stand especially designed by Dr. Henri Van Heurck, the celebrated Belgian naturalist, is, without doubt, admirably suited to the investigation of the Diatomacex. In ‘the form of the Circuit Stage as made by Watson and Sons, of London, supplied with proper condenser and mechanical stage with vernier attachment, it has been used in the preparation of the present work with much satisfaction. The drawings have all been made with an Abbé camera lucida, a 3 mm. objective and a No. 10 eye-piece, producing a magnification of about 800 diameters. All illustrations are from actual specimens in my cabinet or, in a few instances, from slides sent me by friends. In the measurement of striz and puncta, the num:ber in ten microns is stated, and will be found to be approximately correct in most of the drawings, except when the number is in excess of twenty in ten microns, in which case it is impossible to represent the markings accurately on figures of the magnification adopted. All drawings are from specimens in this locality, except in a few cases mentioned in the text. INDEX (SYNONYMS IN ITALICS) PAGE Achnan thes. sisiiscuase de racks ae ans ese 58 revi pes: Ages isis isos. omkatciet sc BAA eee eked 59 coarctata (Bréb.) Grun...................0-. 59 danica (Floegel) Grun.................-00005 60 Odes! Gruber cs oe nce ye iw eee ees 59 inflata (Kuetz.) Grun............... 0.0000 ee 59 lanceolata (Bréb.) Grun.................-.-.- 59 linearis forma curta H.LS................--- 59 longipes Ags io ccc.cick imo hon reece eee 58 subsessilis Kuetz............- 0000s ceeeeeeee 59 Acctitie ins 5. sccccsseveves sc AGcounealss 2s bce ceeentiaied 02 Sat 54 punctate Lewis icc ci casccwtae sakes saeess 54 ActincyClisiasesos ss cseasw seca eaeeant seas s 26 barkleyi var. aggregata Rattr............ renee SOE ellipticus var. delawarensis n. var............. 27 moniliformis Ralfs..................--28-ee- 27 Actinoptychus. .sjc5-.cuswes seed pepaseh ae ges ers 24 elbulgsa TED R sees 6 aisccreciatin acy eae Rene aGe cane wee a 24 heliopelta Grun. var.? esas ACU tad mage asece tes 25 omphalopelia Ebr..... 2.2.22... esc e seen 24 dulatus (Kuetz.) Ralfs.................04. 24 vulgaris var. interrupta n. var................ 24 Amphipleura 3.0: v..cc54c0sae cyaccaas bates Ae e884 78 pellucida Kuetz..............0.. 0.000000 eee 78 ratilans (Trentepobl) Cl...................5. 73 Amphiprora..:'o5:20s'ess lessee corseeiinds ccsads 68 glata Kuetsisc sconces epee oy apeaaes ese 68 conspicua Grev....... 26... cece eee eee 68 lepidoptera Greg... 1.2.0... cece cee eee eee 69 Ornata Bailes cc -ced csc istee Anos cis Geagecseusie dee Renee 68 pahidosa Wm. Sm............. 02. c eee eee 68 pulchra. Bail. cic ss cian bec seeder ee Saale 68 Amphitetras antediluviana Ebr............0 20 cee ee eens 32 tessellaia Shad... : ocencvus sc i scaseeee aces 32 Amphotaioccsiccceeins sss cteaew ens oxcaieaiinn ss san8 65 acuta Greg........... Sd sar Sok ausidaeeabe’ see 66 angusta var. eulensteinii Grun................ 67 aponina Kuetz... 2.2.20... 00 cece cece eee eee 66 arenaria Donk... ............ 002s 67 areolata Gruliss.. oc das deacon sewmetiiea. sa ncatis 66 coffeiformis (Ag.)Kuetz...............-2.005- 66 CTASSA GLE R oo bec ee eeadoisan be «acdabialarerd ead = atte 65 eulensteinit AS... eee cece eee eee 67 gigantea var. fusca A.S............. nieinadueateite 65 insecta Grun....: 2... eee cece eee ees 69 Levis Greg: 3c eset aa denntew es saees 66 hineolata:Ehr. << + ..-ssec.0e055 to-aieee 24028 66 mucronata H.LS.......... 0006s cece ee eee 69 obtusa Gregice.is. cs dicauey sak eeeaee vee sens 67 ocellata var. cingulsta Cl...............2..-- 67 Amphora—Continued. PAGE ostrearia: Breb 65 os eke eikereasacd Se oa ek ithe 66 ovalis (Bréb.) Kuetz................. eee ee 65 var. libyca (Bhr.) Cl... 2... eee 65 var. pedicuius (Kuetz.) Cl............... 65 plicata Greg............. a alathagite: on alr ea ca eee 66 porcellus Kitton............ Salngln wage Hale 66 proteus: Greg cocci sce 5 onsen wea 65 quadrata Bréb... 1.2... ee eee ee .. 66 FObUStA Gree. dws eos dain d cee wee 65 Salina: WAS SW sasiesso sat aiea occ scae ees 66 wile: Cl ipacsetes ideas iieial arsreedec aeeuchebeaB ale eins Bee 66 (ADOM CONES 05 gi ce se lsscid Sa waa aeel be ae ans ae Ses 80 follis (ohr:) Clive. s cased cc cicioce cee ct sasaaey 80 serians! Brébe. 2 siwcaod.ece es vais Oe ae aoe 80 spherophora (Kuetz.) Cl... ..............06- 80 Anorthonels ss 50.254 sassoten ee csiecdn deci vias eens 56 excentrica (Donk.) Grun..................4. 56 Asterione lla sc c65:. sissies oo aie shasta eee ae a aaron 50 formosa Hass.........2..6.0 cece cece cece 50 WA ta HeIb. ss ocsisecsiuisn ow suaeeeteblanacaasewkigas 50 Attheyaic. ove fon. ckiascaseos o.aagennas Sites tuceee ae 33 Cecora: WeSbis:cisees.d.e5csiacdiswis esd ine, santececeumes 33 Aulacodiscuss.2. 4 ccsns sis easewen ied dea a caanee 26 argus (EBbr.) A.S.iix's.005 dueenwis yteg sep oseuan 26 Auliscus dissec cagtiwatins es wena raed oe s SORE eS 238 exlatis Bailie ccs eod rine eng acide 29 pruinosus Bail... 0a yeguics awe mate 28 punctatus Bail.........0.....0.. 0.0. e cee 28 sculptus (Wm. Sm.) Ralfs................... 29 spinosus Christian................... saeoentie 29 PRURICUL Ss Mtns oc ee oteean daustoa echo! estys ad sarsbasniebete 69 insecta (Grun.) Cl..... 0.00... c eee eee eee 69 mucronata (H.L.S.) Per..................... 69 Bacillaria paradora Gmelin............0 00.0. 119 Biddull pois 0. p3.csikin oo 4 seman vo a eR eg 31 alternans (Bail.) v. IA coke Patekta areca Me eevee: 33 antediluviana (Ehr.) V. H................... 32 biddulphiana (Smith)...............0000.0.0. 31 davis (Phe) Me A cece css oe sac cagescen cece 31 granulata Roper............ 2.0.0 e cece eee 32 Levis Bbrieciicseinecedss etna oss dee acuaeaows 33 pulchella Gray... 20.6... eee cece 31 reticulum (Ehr.)....... Bieweesiey renee aah neha e 33 rhambus (Ehr.) Wm. Sm.................... 32 smithii (Ralfs) V. H.............00.000000.4. 32 turgida (Ebr.) Wm. Sm..................0... 32 BrébissOnla cccccacne ose ecalicadedasamewloanga ees 79 beeckii (Kuetz.) Grun............00.00000... 79 palmeriin. 86.506 bekins ehh oaenns edocs 80 138 Caloneis: cszcrccdseieagees susdseemn es ee 81 brevis var. vexans Grun...............000005 82 formosa (Greg.) Cl............0. 0c c eee eee 82 liber (Wm. Sm.) Cl... 0.0.0... 0c. eee eee ee 81 permagna (Bail.) Cl.................0 002 ee 82 var. lewisiana n. var..............00 200s 82 powellii (Lewis) Cl...............-..02000 008 83 silicula (Ehr.) Cl......... 0.0.00. c eee eee 81 var. inflata (Grun.) Cl................... 81 trinodis: (Lewis) ss05044 0% ses andes ees asauues 81 Wal Gil Chin crewoinenae ss satommedaeniie saree 82 Campylodiscus...........0.. ss eee cece eee eens 129 argue Bails... 2.0.5 casas eaat enter ee Ss 130 echeneis Phiri: .cissnenus ce seceexe ees se858s 130 hibernicus Ebr..............0. 000.0 c eee eeeee 130 Cerataulus SmUhre RAs, crsicwie aad. Bi eiehe Reson eas 32 turgid its Elifonsscaxanvieies oseeaies does 15% 32 COCCOMEIS 0 5255 crise cecseutidtcdvd aad Sond canienaiieeneisaate Spams ate 57 GIFUp ta: Grego. k neieiecslentisssreiess distawiadeoi nt haces 58 pediculus: Ehf;.....¢ ca. sass se sasauaw ose cee 57 pellucida: Gruttiwsiic0ci0 e005 cecwseencoane ses 58 placentula Ebr, «sc scsceoses eeceeeneed sais 57 var. lineata (Ehr.) V. H................. 58 scuitell am BG secsctisrecersanatin us aonsitercitieancainswones 57 var. ornata Grun........-.---2202 eee eee 57 Cocconema asperitim FLD. ia cxscenwieaas exiregaiareerenees 61 Colletonema neglectum Thwaites............-002eeesceeee 95 vulgaris Thwaites............ 0.2 .ce eee e eens 77 Conferva biddulphiana Smith............2.0.000e0 cee 31 ‘floctulosa Roth ss s<.cccusacwend ts eseewaw ones 36 moniliformis Mueller............2.-600 0000s 16 nummuloides Dillw............. 2000000 16,17 rutilans Trentepohl..............-....2..04. 78 Coscinodiscus.......... 000 ce eee cece eee ee neces 21 argue Whrisc 26a cossc wis ueseese se ectesamees 23 asteromphalus Ehr............-...-2000e000s 23 var. omphalantha Grun.................. 23 biangulatus A.S........- asa aha agasare cave cardzeraeannie 23 Gomaritis As !S-oieeisicic- a0 ecaraveiaseleia wie eine aca aienbcwesls 22 excentricus Ehr..............020-ee cece eens 21 "var. perpusilla Grun...............-.000% 21 lewisianus Grev............. 2. eee eee eee eens 24 linéatiis Bhirsisssccissccoeeaceudees caved 21 marginatus Ehr.............6 00.0 cee eee eee 22 minor Wm. Sm..........0-. 00sec eee eeeeeees 14 nitidulus Grun, . 062650806 eee eeeecweaes deans 21 nitidus Greg: sia scseiiees ceures anqines vewaees 21 oculus-iridus Ehr........... pctens veaede Ried We lereraers 23 polyacanthus Grun........... 06. c ec ee eee e ees 22 radiatus Ehr............. 200 ee sce cece eeeees 23 striatus Kuetz... 0.00.0 ccc cece eee eee eens 19 subaulacodiscoidalis Rattr................... 23 sUbtilis: BWP: 3: beg eoto te . SPH SP gh ody ode O55 8 POS ele gregusee? gee aes HOSHS SHES OSgeeB Fac ag gh goed pOOHTITOHIIVTWI gH HIT NOVA Sedy, ln 0200000 CSSPS00900 Seco a5 OG 200900999 2999 es c o¢ se Be oe S029 99VII355 ° °° 3093909099 ° D2 3 8s 290909299 e ee oo oOo eo ° 6 eon ecnaaeooaoe AD NATUR. DELIN. C.S. Boyer Fic. 1-2-3 45-6 8-9-10 11-12 13-14 15-16 17-18 19-20 21 22-23 24 PLATE 8 Pace RHABDONEMA Rhabdonema arcuatum (Lyng.) Kuetz................. 35 Rhabdonema adriaticum Kuetz................0...0-5- 36 Rhabdonema minutum Kuetz..................200.005 36 TABELLARIA Tabellaria flocculosa (Roth) Kuetz...........0..0000008 36 Tabellaria fenestrata (Lyng.) Kuetz. ................-- 36 a GRAMMATOPHORA Grammatophora marina var. subtilissima (Bail.) V.H.. 37 Grammatophora angulosa var. hamulifera (IXuetz.) Grun. 37 Grammatophora marina (Lyng.) Kuetz............... 37 Grammatophora islandica Ehr.............00.0...0.0.. 37 Grammatophora serpentina Ralfs. .................... 37 STRIATELLA Striatella unipunctata (Lyng.) Ag. .................0.. 38 Striatella interrupta (Ehr.) Heib..................... 338 ATTHEYA Attheya decora West.........0..0.0.00. 0000000 c cece eee 38 Pate s DWATOMACE.E OF PHILADELPHIA See alti tS . ees | a Ini Lie eS i fe RSs byktres gus ica vant eel HOOT TTA, > : rs i % we AD NATUR. DELIN. CLS. Boyer Fic. 1-2 3-4 67 8-9 10 il 12-13 14-15 PLATE 9 Pace LICMOPHORA Licmophora flabellata (Carm.) Ag. .................05. 39 Licmophora lyngbyei Kuetz............0..2..0...0.00- 40 Licmophora ehrenbergii (IKuetz.) Grun................. 40 Licmophora paradoxa (Lyng.) Ag ......-...20..602005 39 Licmophora ovulum Mer. .........-2-.2.20.20-00000005 39 Liemophora baileyi (Edw.) Grun... 2.2 .....0000-.0.2055 40 Licmophora gracilis (Ehr.) Grun..........2.......2..65. 39 Licmophora gracilis var. elongata (Kuetz.) De Toni..... 39 Licmophora tincta (Ag.) Grun..... 22.2220. 2 2.02. 40 Plate 9 DIATOMACE-E OF PHILADELPHIA AD NATUR. DELIN. C. S. Borer PLATE 10 Fic. Pace MERIDION 1-2-3 Meridion circulare (Grev.) Ag.........5-.000 2000200055 40 DIATOMA 4 Diatoma vulgare var. grande (Wm. Sin.) Grun .......- 42 a Diatoma anceps (hr.) Kirchn...............0...---- 42 7-8 Diatoma hiemale (Lyng.) Heib...............2 000004. 42 9-10 Diatoma vulgare Bory. .............2+--- #3 taancntsh Cae 42 PLAGIOGRAMMA ll Plagiogramma tessellatum Grev..........--.0.05.2065 43 12 Plagiogramma obesum Grev.........---.000+0+2000005 43 13 Plagiogramma pygmaum Crev..........-.-.....0.000- 43 14 Plagiogramma wallichianum Grev...............-..-- 43 EUNOTOGRAMMA 15 Eunotogramma leve Grun............-.2...00 00000 ee 33 OPEPHORA 16-19 Opephora schwartzii (Grun.) Petit.................0.. 43 17 Opephora pinnata var. lanceolata n. var..............- 44 18 Opephora pacifica (Grun.) Petit...................-.. 43 FRAGILARIA 20-21 Fragilaria virescens Ralfs.................0....0-005. 44 22-23 Fragilaria arctica Grun.................0 0.000 e ee eee 44 24-25-27-28-29 Fragilaria undata Wm. Sm.................... 44 26 Fragilaria undata Wm. Sm.jvar.?............-......- 44 30 Fragilaria construens (Ehr.) Grun.............2......- 45 31 Fragilaria harrisonii (Wm. Sm.) Grun................. 45 34 Fragilaria capucina var. mesolepta Rab............... 45 35 Fragilaria parasitica (Wm. Sm.)...-........-.....-.. 45 36 Praga ria Spi 22 sis gio. d abe uci acd he augers vaneustoaverdiaacs oes Bee 45 37 Fragilaria linearis Cstr................-0-.0.0.00-002- 45 RHAPHONEIS 38 Rhaphoneis amphiceros Ehr.......................0. 46 39-40 Rhaphoneis amphiceros var. rhombica Grun........... 46 41 Rhaphoneis belgica var. intermedia Grun............. 46 SYNEDRA 32-33 9 Synedra radians Ruetz.....-........--5.0-.20-202220 0. 49 Puatre 10 DiATOMACE.E OF PHILADELPHIA CT yt i ~ i t S. BOYER i AD NATUR. DELIN. © PLATE 11 Fic. Pace — SYNEDRA—Continued 1-5-6 Synedra ulna (Nitzsch) Ehr. Sporangial............... 47 2 Synedra daiica Kuetz............20.0.2 200002 ve. 4S 3 Synedra biceps (Kuetz.) A. S............022. 22 e eee 48 4-7-11 Synedra ulna (Nitzsch) Ehr.............2.......-.-. 47 8 Synedra capitata Ehr................000 0.2 eee ee eee 48 9-18 Synedra acus Kuetz... 2.2... 2-2-2 0-2ee eee eee e eee 48 10 Synedra fulgens (Grev.) Wm. Sm.................-.-- 50 12-13 Synedra goulardi Bréb..........6. 2-2 000s0ceeeeeeeee 48 14-15-16 Synedra pulchella (Ralfs) Kuetz. ...............2200. 48 17 Synedra pulchella var. abnormis Macchiati?........... 48 Prater 11 DiaToMAck.£ OF PHTLADELPITA Semen terre T TEC art dud Ter, & tease SIME TT eT ea Tenet Ta wt Tal: fea a rt ge AU ALNUO Gta Laan ag ee re ara 2 eat ae Vie ote hte its = Cr ee MEER See | eo i omit TTT tees 0 Vena 2H Sts alte ~ Hgbisie Soeepe AUT TLNTTTTET—UENTTTTTMAMNTA AMMA mT LUUUY QQ erty eae ear ee eab else tetabrageseg tts ATIMUTTTATTATATTMT TT TTT RT TT TT a cen atta CERLUMSLSUAALADMIUELLLA CATDRLAULU TLD AUCL UD MOMS FU OULU LOREM COU YEOH PURER ECE LEE E OUE OO CMOS gd at PULLEY YULbaeas tad fairy AD NATUR. DELIN. C.S. BovEr Fic. os Gt de OF too 9-10 ll 12-13-14 24-25 PLATE 12 Pace SYNEDRA—Continued Synedra oxyrhynchus var. undulata Grun.......--.--- 48 Synedra pulchella var. flexella n. var.....-...-.------- 49 Synedra affinis Kuetz..............222.-222222--2--- 50 Synedra affinis var. tabulata (Ag.) V. H......-..------ 50 Synedra vaucherie var. parvula (Ruetz.) Kab......... 49 Synedra affinis var. parva (Ruetz.) V. H...-.....----- 50 Synedra radians (Kuetz.) H. L.S.......2.-2-.------- 49 DIMEROGRAMMA Dimerogramma marinum (Greg.).....---------------- 46 Dimerogramma surirella (Ehr.) Grun.........-.------ 46 Dimerogramma minus (Greg.) Ralfs..........- steal 47 TRACHYSPHENIA Trachysphenia australis Petit... ........-2-2.22-2...2.2. M7 ACTINEELA Actinella punetata Lewis... .........222-0--.02--2-05- 54 ASTERIONELLA Asterionella formosa Hass........2-...2-..2-.20-02005 50 Asterionella inflata Heib...............-.-. syreeee es 50 EUNOTIA Eunotia hemicyclus (Ehr.) Ralfs..............00...0. 53 Eunotia lunaris (Ehr.) Grun......2....2....00 0000 53 Phare 12 Toate. Ee OF PRO LADELPHIA TEA ee orev Gt ce TA TUBTETTTTMan aegneaM tag URNS anne careers «HIRE ed a Tr sb RHUL AYO o AUTTUTTTDUT ITT T0788 * Hh SN iy ML HH LSS UERTS 858888 Soe ade Hpgudasaeie> & GEEANEE TN uuu Nl i i A a DNattUn. DELIN. C. S. Boyer Fic. 1-2 67 8-10 ll 12 13 14 15 16 17-22 18 19 20 21 24 25 26 27 30-31 32 PLATE 13 Pace EUNOTIA—Continued Eunotia major (Wm. Sin.) Rab. 2.22222... 51 Eunotia gracilis (Ehr.) Rab. 2.2.0. 0000000000..2200000- 51 Eunotia major (Wm. Sm.) Rab. (intermediate form) ... 51 Eunotia prwerupta Ehr. 2.2... .....2....02.00..00002000- 53 Eunotia pectinalis (Kuetz.)...........2.........2.:... 52 Eunotia pectinalis var. undulata Ralfs. .... ety shits iattekcs 52 Eunotia pectinalis var. solicrolii (uetz.)..............- 52 Eunotia luna Ehr. var.?.......2......0..2....222002-0- 52 Eunotia pectinalis var. ventricosa Grun..............-- 52 Eunotia robusta Ralfs (Bysealaris Ehr:) s..i0 00000288504 53 Eunotia robusta Ralfs (E. prioritis Ehr.)............... 53 Eunotia robusta Ralfs (E. decadon Ehr.)............... 53 Eunotia robusta Ralfs (E. octodon Ehr.)............... 53 Eunotia robusta Ralfs (E. heptodon Ehr.)............. 53 Eunotia bactriana Ehr. ..........0.0.0.0..0022.020.020-. 54 Eunotia prerupta var. bidens Grun. .................. 53 Eunotia bidentula Win. Sm... 2... 54 Eunotia robusta Ralfs (E. diadema BE) oes et socctcsaneasnaus 53 Eunotia prerupta Ebr. var.? 22.0... 00.0.0... 0000. 53 Eunotia robusta Ralfs (E. triodon Ehr.) ee 53 Eunotia robusta Ralfs (E. tetraodon Ehr.). ............ 53 Eunotia formica Ehr. var.?.......0.0..0.00000000.00000- 54 Eunotia Saal BiRikatcrsievicysyaaaaar aoa eens 53 WH OUAS P20 o..ca.den tren shoud Ave wttede oe-orateereminas 54 Eunotia veneris Kuetz. ...............0..0. 00000 ce eee 52 PLatTe 13 DiaToMace.E OF PHILADELPHIA TTD eS hana PL = a9 S es AD NATUn. pein. C. 8. Borer 8-9 10-11 PLATE 14 Pace AMPHIPRORA Amphiprora pulchra Bail. ......................------ 68 Amphiprora alata Kuetz.................0---22-2200005 68 Amphiprora conspicua Grev. .............-.-.-- .... 68 Amphiprora paludosa Wm. Sm..............--.------- 68 Amphiprora ornata Bail. ...................2- 22-025 6S TROPIDONEIS Tropidoneis lepidoptera (Greg.) Cleve. ................ 69 SCOLIOTROPIS Scoliotropis latestriata var. amphora Cleve............. 69 Piate 14 DratoMaCE-® OF PHILADELPHIA | mand ROA ett Sean baa i en ee Se eee a et ae ties bs a \ nent “S. Boyer DELIN, ( AD NATUR. Fic. em Oo Mm 5-6-19 8-18 9-10 il 12-21 13 14-15 16 7 20 PLATE 15 PaGE AMPHORA Amphora robusta Greg. ..............-2.+ an ere A 65 Amphora crassa Greg... . 2.2.0.0... 000. e cece eee eee 65 Amphora obtusa Greg............ 20.0000 c cece eee eee 67 Amphora proteus Greg. ...........00..0.0 eee eee eee 65 Amphora ovalis (Bréb.) Kuetz. ..................22055 65 Amphora coffweiformis (Ag.) Kuetz. ................255 66 Amphora lineolata Ehr. ...........0.0.00000 cece eee eee 66 Amphora areolata Grun. ............00000 0c cence eee 66 Amphora ostrearia Bréb...............00.000e002e22. 66 Amphora levis Greg. ............ Sry aya eiaccreans ee pte eases 66 Amphora ocellata var. cingulata Cleve................. 67 Amphora angusta var. eulensteinii Grun. .............. 67 Amphora arenaria Donk... 2.........0.0.0-0 cece eee ee 67 Amphora acuta Greg............. 0.000 cece eee cece eee 66 AURICULA Auricula mucronata (H. L. Smith) Peragallo. .......... 69 Pate 15 DiaTOMACE-E OF PIULADELPHIA ee see | RTS me eo ee See $ eee | Bey! a Bea nis. sai 0 BE Wah i ‘ eat JB oe aS Bo gee |g OOP ee Sa ei = > fw oe) A \' ered > f OF aes ae ape ae leeks ee) f ties panes des. 2 Ne TR” ON N SNC RD ay ett " hy we ony yi yy TSS Senn A TTA i anseenaseusesels Hiss 20> 5 Qos C.S. Boye AD NATUR. DELIN. Fic. 1-2 3 4-5-6 7-8 9 10-11-12 13 14-15 16-17 18 19-20 21 23-24 25-26 27-28 - 29 30-31 PLATE 16 ACHNANTHES Achnanthes longipes Ag...............0-000000 : Achnanthes brevipes Ag.............0.000 00005 Achnanthes subsessilis Kuetz...... .. .... ... Achnanthes inflata (Kuetz.) Grun......... 0... Achnanthes coarctata (Bréb.) Grun...........-. Achnanthes lanceolata (Bréb.) Grun............ Achnanthes danica (Floegel) Grun. (lower valve) Achnanthes exigua Grun.............-.....04. Achnanthes linearis forma curta H. L. Smith... . COCCONEIS Cocconeis scutellum var.?..........0.02.5..00-. Cocconeis placentula Ehr...................--. : Cocconeis scutellum Ehr. (upper valve). ........ Cocconeis dirupta Greg. (lower valve)........... Cocconeis pediculus Ehr....................... Cocconeis pellucida Grun..............5....... Cocconeis scutellum var. ornata Grun........... Cocconeis placentula var. lineata (Ehr.) V. H.. . . ANORTHONEIS Anorthoneis excentrica (Donk.) Grun........... Pace PLate 16 VIIA E OF PHILADELP DraTOMACE AD NATUR. DELIN. C. S. Boyer , Fic. an mm Wh = 10-11 12 13 14 15 16 17 18 19 21-22-23. 24 PLATE 17 Pace FRUSTULILA. Frustulia lewisiana (Grev.) De Toni.................. WZ Frustulia rhomboides (Ehr.) De Toni. ...............- 77 Frustulia fhomboides var. amphipleuroides Grun....... V7 Frustulia vulgaris (Thwaites) De Toni................ V7 Frustulia interposita (Lewis) De Toni................. 78 Frustulia rhomboides var. saxonica (Rab.) De Toni .... 77 BRF BISSONIA Brébissonia bovckii (Kuetz.) Grun..........02.....006 79 Brébissonia palmerii n. sp... ..... 0.60.60 c ee eee 80 AMPHIPLEURA Amphipleura pellucida Kuetz...............2..5.0.004 78 Amphipleura rutilans (Trentepohl) Cl..............-.. = a8 ANOMEONEIS Anomooneis serians (Bréb.) Cl... ............00 00008 80 Anomevoneis serians forma minor..................... 80 Anomovoneis follis (Ehr.) Cl..................0000005 80 TRACHYNEIS Trachyneis aspera var. intermedia Grun............... 79 MASTOGLOIA Mastogloia kinsmanii Lewis. ........................ 87 Mastogloia angulata Lewis......... Bs eset dhauressauasyarenehons . 87 Mastogloia lanceolata Thwaites..........0......0...... 87 Mastogloia smithii Thwaites.............02.......04. 87 Mastogloia elegans Lewis........... de AREA omer Se 87 Mastogloia apiculata Wm. Sm.........-.....6.....-, 87 Mastogloia exigua Lewis.................2.0....000.- 87 PLATE 17 DIATOMACE-E OF PILILADELPHIA i hy Hf Ty AW 1 AD NATUR. DELIN. C. S. Borer Fic. CONAaA PR wD em eke eo NS Oo 15-19 16 17 18 20 21 22 23 24 25 PLATE 18 Pace CYMBELLA Cymbella aspera (Ehr.) Chi... 6. eee eee 61 Cymbella cymbiformis (Kuetz.) Bréb...... . een eeee 62 Cymbella cistula (Hempr.) Kirchn................-.. 62 Cymbella lanceolata (Ehr.) Kirchn................... 62 Cymbella mexicana (Ehr,) A.S...........-.2-0.20005 62 Cymbella naviculiformis Auerswald................-.- 60 Cymbella tumida (Bréb.) V. H.. 0... eee eee 62 Cymbella philadelphica n. sp..............- reece aren 63 Cymbella ehrenbergii Kuetz..................22..0... 60 Cymbella heteropleura (Ehr.) Kuetz........ hence 60 Cymbella rhomboidea n. sp.........-...... antrum 63 Cymbella turgida (Greg.) Cl. var.?.0...0.0....0..2.00.. 63 Cymbella sinuata Greg...........2.0..2.. sh Sow ae sens tpg 61 Cymbella ventricosa Kuetz...............-....--205. 62 Cymbella excisa (IKuetz.) De Tont.................... 61 Cymbella amphicephala Niegeli....................2.5. 61 Cymbella cuspidata Kuetz..........0.00. 0220s 60 Cymtella affinis Kuetz. ........00.00.0.00 020 cee eee 61 Cymbella gracilis (Rab.) Ch... 0.0.0.2 22. eee eee 64 Cymbella prostrata (Berk.) Cl... 0.0... ...0..00020085 63 Cymbella ventricosa Kuetz.?.....................000. 62 Cymbella turgida (Greg.) Cl............... Seger -.. 63 Cymbella triangulum (Ehr.) Cl... .......000.00-00000. 63 Cymbella lacustris (Ag.) Cl..... 0.2.0... 6 cece eee eee 64 Pruate 18 DIATOMACE.E OF PHILADELPHIA Vily fii i ww Le WW? \\Wy, WAY i iivs: Whitin ip. im ME NN ZZ Hi Sino OT ee egnr en) | oat i wil if a WW Yin Messe UA X9"E Za ZB A See. Ze\ re p> \\ NY) WT, a — NM aes MY Wp ZENA" ut i i i i ELA —_—T ta ain! omer HENS” { i SANUS Dy mi) TUT Mateus —== can PAD ae eH Awe Wuy tage te. rl Qo Tn Poi eencoec 0c? AD NATUR. DELIN. ( > . S. Beyer Fic. rs 6-12 9-10 11 13 14 15 16 17 18-19 20 BESsge PLATE 19 Pace GOMPHONEIS Goimphoneis mamilla (Ehr.) Cl...........0..0...2.0.-. 70 Gomphoncis herculaneum (Ehr.) Cl..............0.0..- 70 GOMPHONEMA Gomphonema montanum Schum. ..................--- 71 Gomphonema geminatum Lyng. .................-..-- 71 Gomphonema acuminatum var. turris (Ehr.) Cl. ....... 71 Gomphonema lanceolatum var. insignis (Greg.) Cl...... 71 Gomphonema acuminatum var. coronata (Ehr.) Cl. .... 71 Gomphonema constrictum Ehr...................----- 72 Gomphonema sphxrophorum Ehr. .................--. 72 Gomphonema acuminatum var. turris (Ehr.) Cl.?....... ve Gomphonema ventricosum Greg.................2-6--- 73 Gomphonema intricatum Kuetz. ..........2....2..2--- 72 Gomphonema wyuale Greg. ...........-.-.0.00000000% 72 Gomphonema sarcophagus Greg.....................-- 72 Gomphonema parvulum var.micropus (Kuetz.) CL..... 73 Gomphonema angustatum Kuetz...................... 72 Gomphonema acuminatum var. trigonocephala (Ehr.) Cl. 71 Gomphonema augur Ehr....... 2.22.2. 2 02-200 e ee eee ee 72 Gomphonema capitatum Ehr....... 2.22. .2..0-2..-0.4. 72 Gomphonema olivaceum Lyng........................ 73 Gomphonema brasiliense var. demerarze Grun.? ........ 73 RHOICOSPHENIA 25-26-27 Rhoicosphenia curvata (Kuetz.) Grun. .......... Ean 56 PLate 19 DriaToMAceE-E OF PHILADELPHIA mn AAS HAWS ZW - HY i Si MM onus MMA ie » Him AWWW \ a etee at S Bee ee Ril) \ : Tal WE Me dase, ti ER A) Ae DELIN. CLS. Boyer AD NATUR, Fig. 1) 7-8 10 11 12 13 14 15 16 17 PLATE 20 PaGE ; DICTYONEIS Dictyoneis marginata var. maxima n. var.............. 79 Dictyoneis marginata var. commutata Cleve. .......... 79 Dictyoneis marginata var. typica Cleve................ 78 DIPLONEIS Diploneie srabro var. pandura (Bréb.) Cl.............-. 85 Diploneis campylodisecus (Grun. )Cl............ arches 86 Diploneis gruendleri (A. S.) Cl....2 220.002.2002 85 Diploneis crabro Ehr. var.?..........020-0.0.000200005 85 Diploneis excentrica n. sp........0 2.0... e eee ee ee ee 85 Diploneis fusca var. delicata (A. 3.) Cl... 22 0....0000.. 85 Diploneis puella (Schum.) Cl.................2.....2.. 85 Diploneis crabro var. pandurella Cl.?.................. 85 Diploneis elliptica (Kuetz.) El... 22.20 2.0.0.0..0..- oeee 84 Diploneis crabro var. expieta (A. 8.) Ch... 22.02.22... 85 Diploneis gemmata (Grev.) Cl.................0...... 86 Diploneis smithii (Bréb.) Cl... 222.2200 00000000000022. 84 NAVICULA PLATE 20 awit: wee TM ec oe A By UU UU UU UU EE EE EEE GIL CUE UU U LUUEULUUES Oe te . v AUIS aad _ a _ ) alin ) ~_ vas DHisaaes s | Be UE YE OUCOVOME CULV UY YEvE OY CELE EL EE MOIHOOG VU ENM EY CULTS eR ee ‘ie Pra TeX \ OF PHILADELPHT. F DIATOMACE ye OOvuv EL CGULEULL UU UD a EY UYU OY USL dD OUVTVVEVEIY HV OAe Lud 1a te AS Y 1 part pris 8 Ae ay par Saab Vibtauy f PIPFIOVATATAT BAM Maat cn Bez. nan 4 co aT. Bho RURAL Nota KUO Pkt (ta Ha MAK OAT TSA). beh 4 4, re oe ETE VS Vern tte CC N “ o rant eof AN 2D 985; LTE L S. Bove EI AD NATUR. DE Fic. aor wn = o 7 10 18 11 12 13 14 15 16 17 PLATE 21 Pace CALONEIS Caloneis permagna (Bail.) Cl....:...............2.0005 82 Caloneis permagna var. lewisiana n. var. ........-..-++ 82 Caloneis silicula (Ehr.) Cli... 0.00... 0 ccc cece eee eee 81 Caloneis silicula var. inflata (Grun.) Cl... 2... ...--00-- 81 Caloneis brevis var. vexans (Grun.) Cl..............-. 82 Caloneis wardii Cl... 6.20.0... 00.0 c cece eee eee 82 Caloneis trinodis (Lewis)..............0.000222eeeeeee 81 Caloneis trinodis (Lewis) var.?................0200005 81 Caloneis powellii (Lewis) Cl................... 0020005 83 Caloneis formosa (Greg.) Cl............-..62 cee ee eee 82 NEIDIUM Neidium affine (Ehr.) Pfitzef..................2-22.0.. 83 Neidium affine var. genuina forma minor Cl............ 83 Neidium aftine var. amphirhyncus (Ehr.) Cl. .......... 83 Neidium amphigomphus (Ehr.) Pfitzer................ 83 Neidium hitchcockii (Ehr.) Cl..................02000. 841 Neidium productum (Wm. Sm.) Cl.................0. 83 Neidium iridus (Ehr.) Cl...............0 02. cece ee eee 84 PLate 21 DIATOMACE.E OF PHILADELPHIA ea) Mi) Ly i iH} SEI afeononv0000000g0000000° 9000000030000 0000000000, pin 22200000000000000000006 2000060000 00000090009080. « at ii (> eS Se ee ee Liddy \ \ \\ ss UD “lf a ~ > ‘ . DELIN. C2 S. Boyes ’ : AD NATUI Fic. aN an rk WO NH = PLATE 22 PacEe PLEUROSIGMA Pleurosigma strigosum Wm. Sm...........-...---.5-- 74 Pleurosigma rigidum Wm. Sm.................-.-.00- 75 Pleurosigma angulatum (Quekett) Cl................. 74 Pleurosigma obscurum Wm. Sm..................° Sones 74 Pleurosigma formosum Wm.Sm................0 20006 73 Pleurosigma naviculaceum Bréb..................00-. 74 Pleurosigma wstuarii Bréb.. ............505- 24200000 74 Pieurosigma virginiacum H. L. Smith................. 74 PLatre 22 DraTOMACEE OF PHILADELPHIA “AD NATUR. DELIN. CLS. Borer Fic. CaONOnrkand ww PLATE 23 Pace GYROSIGMA Gyrosigma strigilis (Wm. Sm.) Cl................-..55 76 Gyrosigma balticum (Ehr.) Cl... ..........0.20 0000005 75 Gyrosigma hippocampus (EFhr.)...................+0.- 75 Gyrosigma simile (Grun.)... 2.2.2.2... 0.00 e eee eee 76 Gyrosigma acuminatum (Kuetz.) Cl..........-.....0.. 76 Gyrosigma scalproides (Rab.) CL. ........-0....2000005 76 Gyrosigma parkeri var. stauroneioides Grun........... 75 Gyrosigma spencerii var. nodifera Grun.............-- 76 Gyrosigma fasciola (Ehr.) Cl..... 20.0... eee eee eee eee V7 Pare 23 DraToMACE-E OF PHILADELPILIA AD NATUR. DELIN. C. 5S. Borer PLATE 24 Fic. Pace NAVICULA 1 Navicula maculata (Bail.) Cl......................05. 90 2 Navicula protexta Ehr.............-. 00202200 sence ee 92 3 Navicula latissima Greg................ cea bbehere ler 90 4 Navicula irrorata Grev..........000.. 0. cece eee eee 93 5 Navicula latissima var. elongata (Pant.) Cl............ 91 6 Navicula fuchsii Pant.........0....0.. 00002000 eee eee 91 Pia tvoMACE.E OF PHILADELPHIA seoes . wP POEM epee aos ate ‘ eaessat ATE y & ‘ HL ATUR. DELIN. C. S. BOYER er Fic, ! 1 Se eee PLATE 25 Pace NAVICULA Navicula tumida (Bréb.) Cl..............0.. 0 eee eee 99 Navicuila brasiliensis var. bicuneata Cl. forma constricta. 92 Navicula delawarensis Grun........... oo uchestyaiuens aay 92 Navicula pusilla Wm. Sm..... 2.0.0.0... eeeee eee eee 91 Navicula humerosa Bréb.............00+- ee ee eee eee 91 Navicula spectabilis var. emarginata Cl............... 94 Navicula pusilla var. subcapitata n. var............... 91 Navicula punctulata Wm. Sm.....................04- 92 Navicula lyra Ehr. ......... 0... ..0cceeeeeeeeceeeees 93 Navicula hennedyi var. manca A.S..............----- 93 Navicula hennedyi Wm. Sm............-.. 0020000005 93 Navicula lyra var. dilatata A. S.............-2--..055 93 Navicula yarrensis Grun................4.00-20-20 00 101 Navicula yarrensis Grun. (smaller form)............-.. 101 3 » soe. Phare MACE.E OF PIILADELPHIA TO Dia . fiit i Wi, “if tify ih i} aa ii eenaiyy HY, Hit ti ; ° gut Pomakt ALU ne { i. itt. Leahy * Waa AA ACARNRENNN RIE Sealimrgepap Sa uN sh eesennnagtat cae WW ti i (AMDUAAH IIL fase mn VAY ALY a Nyy y ask ys WAN AS \ R AD NATUR. DELIN. C. 8. Bove Fic. Oe Oo to ona 18 PLATE 26 Pace NAVICULA Navicula cuspidata Nuetz......00.0000200000000000065 100 Navicula cuspidata var. ambigua (Ehr.) Cl............ 100 Navicula spicula (Hickie) Cl... 20... 00.6.0..020.00-- 100 Navicula integra Wm. Sm.......20000000 000022022 99 Navicula mutica Kuetz...........0..-0-5.0 000002 e eee 97 Navicula americana Ehr............0...00..00--0000- 98 Navicula pupula var. bacillarioides Grun.... ......... 98 Navicula bacillum Ehr............0...0.0.0..02-000 0000 98 Navicula semen Ebr.........).22-0-60 0000 e eee ees 98 Navicula atomus Nevgeli...........5.0020000200 00 ee eee 100 Navicula minima Grun...........0.0.000.00. 020 e cece 98 Navicula ramosissima (Ag.) Cl... ......00..-2-200200- 95 Navicula crucigera (Wm. Sm.) Cl. 2... ....0.......... 100 :Navicula viridula var. rostellata Kuetz............-... 95 Navicula radiosa Kuetz...........-.000000000 eee eee 94 Navicula gracilis var. schizonemoides (Ehr.) V. H...... . 95 Navicula peregrina Ehr. ...........0.02..2.02..-2004 94 Navicula cyprinus (Wm. Sm.).........- siGitrh gh Mabey ee cute 95 Navicula reinhardtii Grun..............0....0...220.. 95 Navicula lanceolata var. arenaria (Donk.) Cl........... 95 Navicula salinarum Grun... 2.2.2.2... eee 95 Navicula gastrum Ehr. ............0.0...0000 000000 eee 96 Navicula anglica Ralfs. 2.2.2.0 0 0.00.02. cee eee eee 96 DIPLONEIS Diploneis oculata (Bréb.) Ch... 2.2 86 STAURONEIS Stauroneis frickei var. angusta n. var. 2.0.2.0... .... 88 Puare 26 DIATOMACE.E OF PHILADELPILLA Hil SW i a! =< AN... * LAA OI, ENN eh "OS. Boyer AD NATUR. DELIN, € Fic. CON OAarh wd = i an 12 13 14 15 16 17 18-19 20 21 23 24 PLATE 27 Pace STAURONEIS—Continued Stauroneis phcenicenteron Ebr. .................-00-- 8&8 Stauroneis acuta Wm. Sm. .................2.02000005 89 Stauroneis americana A. S..........0000 0000 cee eee eee 89 Stauroneis anceps var.?.... 020... . 022 c eee eee 88 Stauroneis anceps var. gracilis (Ehr.) Cl............... 88 Stauroneis salina Wm. Sm............2...00200200005 89 Stauroneis a” .eps var. amphicephala (Kuetz.) Cl... ... 88 Stauroneis anceps var.?. 0.2... eee 88 Stauroneis anceps var.?. 2.2... eee 88 Stauroneis crucicula (Grun.) Cl..................0.2. 89 Stauroneis smithii Grun.... 20.00.0000... cee eee 89 NAVICULA Navicula lacustris Greg. ..... . a Ra iebendaysnsy tea Sean 92 Navicula hasta Pantijs ve+s05345 ¢sa0emeer ise enaemas 97 Navicula hasta var. punctata n. var. 2.2... 20... ee eee 97 Navicula punctata var. asymmetrica Lagerstedt. ...... 92 Navicula dicephala Wm. Sm..............2...0200005 96 Navicula placenta Ehr...-......0020 000.0000. 0 eee ee 94 Navicula inflexa Greg..............5.--0-065 P iotee athens 96 Navicula pinnata Pant.?............0.. 000s ee eee eee 96 Navicula oblonga Kuetz...................000 eee eee 97 Navicula pennata A. S...2 06.2205 6.0. cece beeen 96 Navicula pygmma Kuetz...........0.0.0 0000000 c eee eee 94 Navicula humilis Donk. ................000000000005 96 Pate 27 DiaroMAce.£ OF PHILADELPHIA WAL tF Ty A TE AN AY VAY \ A SUALLLILif, WWW” ULC KINA NUIT TE : MW ‘ 18 AD NATUR. DELIN. C. 8. Borer Fic. mW he = PLATE 28 PaGE PINNULARIA Pinnularia nobilis Ehr. .......................222008 103 Pinnularia major var. pulchella n. var.................- 102 Pinnularia dactylus Ehr...................2..-22204- 103 Pinnularia major (Kuetz.) Wm. Sm................... 102 8 Phare DIATOMACE.E OF PHILADELPHIA oti es \ ll oe ee AD NATUR, DELEIN. CLS. Boyer Fic. OOmOnNnan Fr WH = PLATE 29 PaGE PIN NULARIA—Continued Pinnularia gentilis (Donk.) CL............2......2.-. 103 Pinnularia viridis Nitzsch. ..............0...-...--2-- 101 Pinnularia dactylus var. dariana (A. S.) Cl..........-- 103 Pinnularia viridis var. fallax Cl. ................0.2.. 10+ Pinnularia socialis Palmer...................---02-.- 104 Pinnularia wstuarii Cl. ...... oueee x Suaw WS Se ae ee 6S 105 Pinnularia rectangulata (Greg.) Cl.....2-...:..-...-.. 110 Pinnularia trigonocephala Cl. ...........2..-..-..--. 103 Pinnularia major (Kuetz.) Wm. Sm. (small form near P. viridis).......... 0 ....... iste ps a depart noenrannenneaaceeatos 102 Pinnularia dactylus var. demerare Cl...............-. 103 Pinnularia mormonorum (Grun.)..... 0 .......-2-22--2. 107 Pinnularia brébissonii (Kuetz.) Cl.........2.......... 107 Pinnularia mesolepta Ehr....... ew ieee bende anaes 105 Pinnularia termes var. stauroneiformis V. H........... 106 Pinnularia molaris (Grun.) Cl..........0000-0.00000005 105 Pinnularia braunii Grun............-..-.--- shdvevessacs are 106 Pinnularia termes (Ehr.) A. S.........-.-..-.2..02002- 106 Pinnularia appendiculata (Ag.) Cl.......2.222222220.. 106 Pinnularia microstauron (Er. )Cl. var.?.............. 106 Pinnularia subcapitata Greg............2.2-..-20200- 105 ony Puate DiaToMACE.£ OF PHILADELPHIA Ci is = iat wn gi (CUTIOLUTW COAG OOUNUULUWTTLUULL ANAAANNARON, nnn SS ran na iS SS —, = => —> = SS => “Ss pee SATE ey ear aap Tia ik oe Z ae AG ag AN? A ———- Is He UT Tree, woe SS >, e I or te nA r VAAN my ot wD i NNN ZT HI qi a [ ii mene TT | ~~ (WH idtitei seach AML OO MATATATTAATAAN Ay AQ iulll 1 IND inucnNY An 08 TE Tinie LT Me fii. ANOS NN = Germ, Dh Mra MUN) oo SN a me ce see” Nee SLIT _ XX" "oS. Boyer AD NATUR. DELIN, ( Fic. COONS OO hm WN = — ett me WN = © 15-19 16 7 18 21 24 25 PLATE 30 Pace PINNULARIA—Continued Pinnularia cardinaliculus Cl... 2. ...2...000220.0.200006 107 Pinnularia viridis var. fallax Cl,? (var. B., Wm. Sm.?). 104 Pinnularia legumen Ehr.... 2.2... .-2..-.-20.00.0000000 107 Pinnularia legumen var.? .....22...0..-. 000020 e eee 107 Pinnularia gibba (Kuetz.) V. H......0...0.2..02-000- 109 Pinnularia mesogongyla (Ehr.) Cl... 22. 2........... .. 109 Pinnularia acrospheria (Bréb.) CL... 20.0000 22 108 Pinaularia acrosph:eria var. turgidula Grun..... ...... 10S Pinnularia tabellaria (Ehr.) Cl. var.?................. 110 Pinnularia leptosoma Grun. ... 2.2.22... 105 Pinnularia stauroptera var. interrupta Cl.............. 110 Pinnularia stomatophora (Grun.) Cl................-. 109 Pinoularia stauroptera (Grun.) CL. ...............0.. 110 Pinnularia parva (Ehr.) Cl. var.? 2.2.2.0... 02.002. 108 Pingularia nodosa forma capitata Cl... 2... eee. 108 Pinnularia subcapitata var, paucistriata Grun ......... 105 Pinnularia viridis Nitzsch var............0...0....22... 104 Pinnularia viridis var. caudata n. var. ............- 7... 104 Pinnularia mesolepta var. stauroneiformis Grun........ 105 Pinnularia polyonca (Bréb.) Lewis.............0.0.... 108 Pinnularia borealis Ehr.... 2... .....--22.0200.-000000% 109 Pinnularia lata (Bréb.) Wm. Sm... ......0...0......-. 109 Pinnularia borealis var. scalaris (Ehr.) Cl.............. 109 Pinnularia_blandita Me Spee insineee setae ava yasede es 108 PLare 80 DIATOMACE.E OF PHILADELPHIA Seayyya gt nas OONeRI I) TUES A oe _ an NHS ANN c= AAT" \ WE MMW Ui Lt a TTS a“ NUN sos SS wanes MNS La ei cae AN MNT ig ” Caruana nan SAN AW We, — w= ERT > TTT TTT TATRA TREE, is ~— VOM uy genre aan ani suns ot MANNE IW afi waITINTANC = (~ 2 Sey entess) etree RON YO ae a Nwnddiane oa oT nT NU lt, eae ise S59) ANTM. SWSSSSSSSWWW\LLLY TAMAR KOIOKN alae, CULT, “uae ATTEN siyeet Re aa ces 7S SS INN TL LATE LAN TI? ae WA i tp CS Liu 7 Cl HRS 20 Is AD NATUR. DELIN, CS. Boyer Fic. il 12 13 14 15-21 16 17 18 19 20 23 24 PLATE $i 7 PaGE NAVICULA Navicula elegans Wm. Sm................00-.0000005 101 Navicula elegans var. cuspidata Cl. .................. 101 Navicula grevillei (Ag.) Cl... ...0..002 000.0 ee ee eee 99 Navicula libellus Greg... .......0..2..000 00000 c ee eee 99 Navicula palpebralis Bréb............0000000-0-.200055 101 Navicula rhyncocephala Kuetz..............050..00085 97 Navicula cryptocephala Kuetz...................00.. 97 Navicula longa (Greg.) Ralfs................. Pe ctsearkass 97 PINNULARIA Pinnularia brébissonii (Rueta:) Chicees scope cine 107 Pinnularia borealis Ehr. .............-.0.0-00002 00000 109 Pinnularia divergens var. elliptica Grun............... 107 EPITHEMIA Epithemia turgida (Ehr.) Nuetz.............0........ 111 Epithemia argus Kuetz.......0.0.0..00020 000000 e eee 111 Epithemia argus var.?..........0..... 00000 c cece eee lil Epithemia muelleri A. S.7 2.00.02. 0 00.00 c ce cece ee 1ll Epithemia zebra var. proboscidea (Kuetz.) Grun. ...... 112 Epithemia gibberula var. producta Grun. ............. 112 Epithemia musculus Kuetz................... 0.204. 112 Epithemia musculus var. constricta (Bréb.) V. H....... 112 RHOPALODIA Rhopalodia gibba (Kuetz.) Mueller................... 112 Rhopalodia ventricosa (Kuetz.) Mueller............... 113 Paare 31 DIATOMACE-® OF PHILADELPHIA » GEN . NEaaD agi es cents Sfp ta tecermmareacanns ge eg NOS NN 4 , i TE, 40 cris ENE ra eg RB —_——- LY) y yy ANNO HU INS Boyer AD NATUR. DELIN. C. Fic. ON naar wns = 10-11 12 13 14-25 15 16 17 18 19 20° 21 24 © PLATE 32 PAGE NITZSCHIA Nitzschia circumsuta (Bail.) Grun........00.0.....2-- 118 Nitzschia plana Wm. Sm................00..00002 008 117 Nitzschia granulata Grun............00.0..0002020-00000- 116 Nitzschia navicularis (Bréb.) Grun.................... 116 Nitzschia panduriformis var. minor Grun.............. 17 Nitzschia apiculata (Greg.) Grun. ............2...... 117 Nitzschia tabellaria Grun. ...............2..2--0-05- 119 Nitzschia tryblionella Hantasch....................-- 116 Nitzschia bilobata Wm. Sm.....................---- 118 Nitzschia litoralis var. delawarensis Grun............. 118 Nitzschia acuminata (Wm. Sm.) Grun... ............ 117 ‘ Nitzschia amphibia Grun..................000000000- 122 Nitzschia palea (Kuetz.) Wm. Sm.................... 122 Nitzschia fluminensis Grun.......................45. 120 Nitzschia obtusa var. sealpellifermis Grun............. 121 Nitzschia linearis (Ag.) Wm. Sm. ....... cbasan Mas See 122 Nitzschia communis Rab................ 00000202000. 122 Nitzschia clausii Hantzsch......................0005. 121 Nitzschia epithemioides Grun........................ 118 Nitzschia vermicularis (Kuetz.) Wm. Sm.............. 120 HANTZSCHIA Hantzschia amphioxys (Ehr.) Grun...............-... 113 Hantzschia marina (Donk.) Grun..................26- 114 Hantzschia virgata (Roper) Grun. ................... 114 vis a Piare DiaTOMACE® OF PHILADELPHIA Cm Carrer ee CE Cee A SSeS, ™ Ten, Sete idcuinetnnen Mo Seeth tx: ace Ss ceed a oe ee ae is mam oa a ee oe ; Te Crrtrsrrr rt Yaa W aren AD NATUR. DELIN. C.S. Boyer Fic. SN es 18 IND ew o 15 PLATE 33 Pace NITZSCHIA Nitzschia longissima (Bréb.) Ralfs............ Bide 123 Nitzschia intermedia Hantzsch....................... 122 Nitzschia spectabilis var. americana Grun............. 122 Nitzschia sigmatella Greg. .....................00--- 121 Nitzschia scalaris (Ehr.) Wm. Sm. ..................- 119 Nitzschia macilenta Greg.................0....0.00.. 120 Nitzschia insignis Greg. ...............0.000000.000. 119 Nitzschia vermicularis (Kuetz.) Hantzsch ............ 120 Nitzschia longissima forma parva V.H................ 123 Nitzschia reversa Wm. Sm. .................. Sa toshae 123 Nitzschia acicularis (Kuetz.) Wm. Sm................ 123 Nitzschia paxillifer (O. F. Mueller) Heib.............. 119 HOMCOCLADIA Homerocladia filiformis Wm. Sm..................... 123 Phare 33 DiaATOMACE. OF PHILADELPHIA SESS Re tg . I beecseal Ae pe e Sycerass wie eramerea Ny EAE LR as ES FE PRE TT Se ore et es ot tk _ Tee St vrs Liat tpt tts hd 8 epee DRT ott te zi Ce datapath ta dara tenet Aaa somBeaoaeDESD IDLE O99) jes Sr Fertime fd E Sa tate tpt ett | ~ aA I i acetal a cyl nt 5 , - 4 \ Leese reer TIO Ot Pett Rey te ppe | cine ae wo ae C Be as ; = é ee ay 0 3 opodt 000900000000): agora re | mca So. Gene ee 2 ee pe ey eee 2 rrr ASE Ls ad Cee te em Sa dineod Sa om teres ucla aay oe eee eee ee, AD NATUR. DELIN. ©. S. Boven PLATE 34 Fic. PaGE SURIRELLA 1 Surirella striatula Turpin...............2.....000005. 125 2 Surirella anceps Lewis. ....... egestas secenae 128 3 Surirella ‘intermedia Lewis................2......000. 128 4 Surirella arctissima A.S........00 000000000000 00 cee 128 5-6 Surirella delicatissima Lewis. ...................0.0.. 128 7 Surirella intermedia Lewis forma minor?.............. 128 CYMATOPLEURA 8-9. Cymatopleura solea (Bréb.) Wm. Sm. ................ 129 3 Phare DIATOMACE.E OF PRALADELD SETA 5 SAN aT UE an et [ I | Wy ] Wh) Mi H] My, LM Mi ; — f Mf) \ \ . \ \\ wow Ann \ ‘ . Ap Nath ® penx. CoS. Boxer Fic. PLATE 36 Pace SURIRELLA—Continued Surirella elegans Ehr............0.0.0000 000002 eueee 125 Surirella robusta Ehr............00022..000000 000s ees 124 Surirella febigerii Lewis... ..............0.0--0200200- 128 Surirella gemma Ehr...........--22- 06002002020 ee eee 125 Surirella guatimalensis‘Ehr. ..........2..0....-...2... 126 Surirella panduriformis Wm.Sm.................-+..-- 126 Surirella pinnata Wm. Sm. .....................200-. 126 Surirella angusta Kuetz. 7.....0......0.20.0 22: e ee eeeee 127 - ape as . Pp sii DitaroMACE.E OF PHILADELPHIA Pears 36 any STONTTNTTONTOONTND dagoonooonnNn a e 0 i ~ moO “eqgonnocoo0o0 Ls UcpouneN ane so AD NATUR. DELIN. C.S. Boyer Fic. LS) or PLATE 37 PaGE CYMATOPLEURA Cymatopleura elliptica (Bréb.) Wm.Sm............... 129 Cymatopleura elliptica forma spiralis. ................ 129 Cymatopleura marina Lewis..................---2... 129 CAMPYLODISCUS Campylodiscus hibernicus Ehr. ...............----.-- 130 Campylodiscus echeneis Ehr. ...............---+----- 130 DiaToMAce.E OF PHILADELPHIA Puare 3t ' 24 04 a0 5, 44 o*9 ) 2, “eo 999, 9 449 2900," g0 90 0 4040 0? go 4 AD NATUR. DELIN, C28. Boyin Fic. ll 12 13 PLATE 38 Pace Amphora gigantea var. fusca A.B. ......000 62 eee 65 Meloseira crenulata (IShr.) Kuetz.................-.-- 15 Licmophora baileyi (Edw.) Grun..................--- 40 Coscinodiscus polyacanthus Grun.............2..5..0. 22 Ditylum intricatum (West) Grun............-.......- 30 Pyxidiculg cruciatu Ehr........2......02.0200000000- 19 Gyrosigma scalproides (Rab.) Cl...........0......--- 76 Coscinodiscus asteromphalus var. omphalantha (Ehr.) GID sp sdceesvechideamte iene tater voaensoosiradcantoende 23 Rhabdonema minutum Kuetz................-.0.000- 36 Gyrosigma kuetzingii (Grun.) Cl..........0...0-0006- 7 Gvrosigma prolongatum (Wm. Sm.) Cl...............- 76 DIATOMACE.E OF PHILADELPHIA AD NATUR. DELIN. C. S. BOYER Phate 3s = / — a erg eh fio 4 { . Fig. Con nut WH = — nue Ss 13 i 15 16 PLATE 39 Pace Nitzschia spectabilis var. americana Grun. (zone view) .. 122 Nitzschia panduriformis Greg.............. 000 .000005 17 Hantzschia amphioxys (Ehr.) Grun.................-- 113 Hantzschia amphioxys var. major Grun............-.. 114 Nitzschia dubia Wm. Sm..........0...2.002-200 00005 118 Nitzschia amphioxys Wm. Sm..................-.+-- 114 Nitzschia compressa (Bail.)........... Se ateter ee the 116 Nitzschia compressa var. minor H. L. Smith........... 116 Surirella intermedia Lewis (zone view). ............... 128 Surirella arctissima A.5. forma minor..........-..-.-- 128 Surirella ovalis Bréb.. 2... ...0000.00.00 000020222 eee 126 Surirella biseriata (Ehr.) Bréb. .............-.2......- 124 Nitzschia sigma (Kvetz.) Win. Sm. 0.002 2000-00000--- 121 Nitzschia obtusa var. flexella H. L. Smith............. 121 Stauroneis legumen Ehr..................----26-0 0-5 89 Nitzschia obtusa Wm. Sm... ....00000....00200 20 eee 121 Puare 59 DisromMace.® oF PHtL ADELPHIA 16 IS N | Af] NN i) i WELLL 4 H D i if 1 D Wy y > vey, yy Hi il (Ah (AAAI t AD NATUR PLEIN, COS. Boyes Fic. ao ONO Oe OO -_ ne 13-14-15 i6 17 18-19 20 21 22 23 PLATE 40 Pace Caloneis liber (Wm. Sm.) Cl........0.0.0.0.000..00000- 81 Anomeoncis sphxrophora (Kuetz.) Clo... 0.00.00 6-2 80 Nitzschia spathulata Bréb........0.0.00.0.00..0.0000005 120 Stauroneis ? abnormal..................... La 89 Navicula? abnormal........... Rosales cement 101 Podoeystis adriatica Kuetz. ...........0000.0000 ee eee 129 Nitzschia dissipata (IKuetz.) Grun.......0......0...--. 120 Cymbella ventricosa Kuetz. (zone view)..........-.. 62 Navicula radiosa Kuetz. (zone view)................- 94 Detail of Rhabdonema arcuatum (Lyng.) Kuetz..... .. 35 Diatoma anceps (Ehr.) Kirchn. (containing chromatc- phores) jin seoycedenees eenaeeSeseday nd aee ote 42 Coscinodiscus asteromphalus Ehr. (trans. section, after Pelletan’).waicexscanrs ase eg acer mecioaegeaenberrsked ea ire 23 Transverse section (diagram) of Pinnularia showing straight, oblique and grooved raphes................ 101 Transverse section (diagram) of Biddulphia favus show- ing inner punctate stratum (after Deby)............. 31 Transverse (ideal) section of Surirella................. 124 Transverse (ideal) section of Pinnularia, before and alter division cen2e.sewsanuuenen Wee os eee eens 101 Transverse section of Nitzschia linearis (Ag.) Wm. Sm.. 122 Transverse section (diagram) of Navicula............. 89 Transverse section (diagram) of Cymbella. ............ 60 Transverse section (diagram) of Amphora. ............ 65 DIATOMACE.E OF PHILADELPHIA O% att eX) O909 909 AD NATUR. DELIN. C28. 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