MEMORIAL POULTRY LIBRARY ^^ CORNELL m^^^l^^^^S^^sSi 'QJ UNIVERSITY Ij .;.,..^ i . l , I ^., ,„ . i 5 "f/fE GIff Of IY»Y»VWY»V i The references which have been used, are BroVn's " Klassen und Ordnungeu des Tkeir-Reich," Owen's "Anatomy of Verte- brates," Huxley's "Vertebrated Animals," and "Elements of Com- parative Anatomy," and a paper on the "Osteology of the Colym- bus Torquatus," by Coues. These works have been used freely. The author gladly avails himself of this opportunity to express his sincerest thanks to that able comparative anatomist, Dr. Abram Sager, who has had the kindness to examine that part of the man- uscript relating to the bones of the head. Especial thanks are also due to Prof. Harrington, of the University of Michigan, for his valuable suggestions. Hoping that this may be considered an effort in the right direction, and that it may supply a need greatly felt by all teachers of natural science, the author presents this little book to the kind consideration of all those who are interested in the subject. ANN ARBOR, July, 1876. CONTENTS. PART FIRST.— OSTEOLOGY. PAGE. The Skeleton, 9 Vertebral Column, ii Special Description of some Vertebrae, 15 The Sternum, i7 The Coracoid, 20 The Scapula, 22 The Clavicles, 24 Anterior Extremities, - 25 The Humerus, 25 The Antibrachium, 27 The Ulna, 28 The Radius, - " 29 The Hand, 3° Carpal Bones, 3^ The Metacarpus, 32 The Phalanges, 33 Bones of the Pelvis, 34 The Femur, 36 The Tibia, 3^ The Fibula, 39 Tarso-Metatarsus, 39 The Toes, 4i The Ribs, . 42 Bones of the Head, 44 Occipital Bone, - 48 Parietal Bones, - - - - - 50 VI CONTENTS. PAGE. Temporal Bones, 5' Alisphenoid. 52 Basisphenoid, 53 Tympanie, 55 Palatine, 56 Pterygoid, 57 Orbitosphenoid, - - 58 Frontals, 60 Nasals, 61 Premaxillary, 63 Malars, 65 Superior Maxillary, 66 Lachrymal, 67 Vomer, - - 68 Inferior Maxillary, 68 PART SECOND.— MYOLOGY. The Muscular System, 71 Pectoralis Major, 76 Pectoralis Minor, 77 Coraco-Humeralis, 79 Sterno-Coracoid, ' 80 Subcoracoid, 81 Latiasimus dorsi, - 81 Trapezius, 85 Rhomboideus, 85 Teres Major, 86 Infraspinatus, - 87 Subscapularis, 87 Deltoid Major, 87 Deltoid Minor, 88 Tensor Plicae Alaris Longus, 88 Tensor Plicae Alaris Brevis, 89 Biceps, 89 Triceps, 90 Supinator, - - - - - 91 CONTENTS. Vll PAGE. Flexor Tertius Antibrachii, 91 Brachialis Internus, - 93 Extensor Metacarpi Rad. Longus, 93 Extensor Meta. Rad. Brevis, 93 Flexor Metacarpi Ulnaris, - - 94 Pronator Brevis — Pronator Longus, 94 Extensor Carpi Ulnaris, - - - 96 Flexor Metacarpi Radialis, 96 Extensor Dig. Com. Longus, 96 Extensor Dig. Indicis Proprius, 97 Muscles of Posterior Extremities, - 97 Abductor Magnus, - - 97 Sartorius, - - 99 Biceps, loi Semitendinosus, 102 Adductor Longus, 103 Adductor Brevis Femoris, - 103 Obturator, - 103 Semi-membranosus, 103 Glutei, 104 Gracilis, 104 Crurseus, - 105 Vastus Externus, - 105 Vastus Internus, - 105 Quadratus Femoris, - - 105 Adductor Magnus, ... 106 Gastrocnemius, - 106 Peroneus Longus, - 107 Tibialis Anticus, - 107 Extensor Longus Digitorum, log Soleus, no Flexor Perforans Digitorum, no Flexor Perforatus Digitorum, - nl Peroneus Medius, iii Muscles of Back and Neck, nl Longus Colli Posticus et Biventer Cervicis, 112 Vlll CONTENTS. PAGE. Sacrolumbalis, - 112 Longissimus Dorsi, 113 Interspinales, 113 Interarticulares, - 113 Levator Costarum, 113 Complexus, 113 Recti Capitis Postici, 114 Trachelo-Mastoideus, - 114 Rectus Capitis Lateralis, 114 Longus Colli, - - 114 Recti Capitis Antici, 115 Caudal Muscles, - 115 Levator Caudae, 115 Adductor Caudae Superior et Inferior,' 115 Quadratus Coccygis, - - 116 Depressor Caudae, ... 116 OSTEOLOGY. THE SKELKTON. The skeleton of birds is singularly compact and light. The compactness is due to the fact that the bones contain an unusual quantity of phosphate of lime ; while the lightness is caused by the absence of marrow and the pres- ence of air in its stead, in some of the bones. Upon making a transverse section of one of the long bones, the humerus, for instance, of the domestic fowl, the outer, compact part of the bone will be found to be very thin ; while the interior contains a cancellated structure with large intervening spaces. The bones of the skull are so closely united in the adult, that it is difficult to define the limits of each bone. The cervical region is long and flexible, in or- der to secure the greatest freedom of motion to the head. The neck is sufficiently long to allow of the application of the beak to any part of the plumage, for the purpose of cleaning and oiling the same. The vertebrae of the dorsal and sacral regions are, for the most part, immovably articu- lated to each other ; but those of the caudal region admit of the same variety of motion as those of the cervical re- gion. The ribs, which number seven pairs in the domestic 2 lO OSTEOLOGY. fowl, give oft' a peculiar process, which lies over the next rib. In front the ribs meet with the sternal ribs, which are straight bones, passing from the costal border of the stern- um upwards and backwards. The sternum of the fowl is not so strong as that of birds of flight ; but is deeply cut by wide indentures. The anterior extreinities terminate in three fingers, and the hand is not used as an organ of pre- hension. The two halves of the pelvis are united with each other, and with the sacral vertebras. The femur is short, and the principal bone of the posterior extremities is the tibia. The tarsal and metatarsal bones are fused so as to form one bone, the tarso-metatarsus. The foot consists of four toes, three of which are anterior and one posterior. The entire skeleton of the domestic fowl consists of one hundred and sixty-one (i6i) bones. These are as follows: Bones of the head, . . 29 Vertebral column, . . 42 Os hyoides, sternum and ribs, . . 16 Bones of scapular arch, . . 6 Anterior extremities, 26 Posterior extremities, . 42 i6i The bones of the head may be divided into two classes, as follows : Skui: IS Face, ... .14 The vertebral column is divided into four regions : Cervical vertebra?, ... . i^ Dorsal vertebra*, . . h Lumbar and s.icial vertebrae, . i> Caudal vertebrie, ... y 4- THE SKELETON. I I The sixteen bones which are given for the os hjoides, sternum and ribs are as follows : Os hyoides, . . . i Sternum, . . . . i Ribs, . . . . . 14 The bones of the scapular arch are : Clavicles, . . 2 Coracoidsj . . . . 2 Scapulas, .... 2 r> Each of the anterior extremities has the following divis- ions : Arm, Fore-arm, Carpus, . Metacarpus, Phalanges, 13 Each division of one of the posterior extremities consists of the follovving number of bones : Pelvis, ... . . I Thigh, .... I Patella, . . . . . i Leg, ... '2 -Tarso-metatarrus, ... .1 Metatarsal, ... i Phalanges, . . . .14 THE VERTEBRAL COLUMN. The vertebral column is articulated anteriorly to the head ; it extends along the neck, through the upper and ijiiddle part of the body, terminating in a point at the posterior ex- tremity of the animal. It serves as a pillar to which the OSTEOLOGY. Fig. 2. — Ckrvical Vetebre. frame work is attached, thus giving firmness to the entire body, and pi-otecting the del- icate organs of life. It is composed of a number of short, hollow, cylindrical bones, phiced end to end, so as tf) form a tube which contains an important por- tion of nervous matter, the spinal cord. These short bones are called vertebra. Thev \'ary much in size and shape according to their position in the column. These difterences are so great us to require us to di- vide the vertebral column into four regions. These groups are, beginning an- teriorly, 1st. Cervical; 2d. Dorsal ; 3d. Lumbar and Sacral ; 4th. Coccygeal. The cervical vertebra" are four- teen in number, and form the osseoHS portion of the neck. They are easily mov- able upon one another, thus allowing great freedom in the movements of the head. This is necessary in taking Axis, 3. Third Ccn'ical. food and in shifting the center of gravity during flight. THE SKELETON. 13 The dorsal vertebrae number seven, and arc generally con- solidated into a single piece. The ribs are attaclied fo these and they give strength to the body. The lumbar imd sacral vertebrae number fourteen and are so joined that it would be difficult to decide where the lumbar region ends and the sa- cral begins. The coccygeal are movable upon one another, thus allowing the tail to be used as a rudder during flight. The opening through each vertebra from end to end, is called the spinal foramen. That portion of the vertebra beneath, and forming the floor to the spinal foramen, is the body of the vertebra. The other portion is named the an- nular part ; because it encircles the foramen. The body presents for study two extremities, anterior and posterior, and two faces, superior and infei-ior. The anteri- or extremity of the body has a facet, which is concave late- rally, and convex vertically ; while the posterior extremity has a facet which is convex laterally and concave vertically. The posterior facet of the body of one vertebra, fits into the anterior facet of the succeeding one. The superior face of the body forms the floor of the spinal foramen. It is smooth and concave from side to side. The inferior face is more or less uneven and convex from side to side. In most of the vertebrae, it is divided into two lateral halves, by a thin process, the inferior spinous process. The an- nular portion presents an internal and an external part, and an anterior and a posterior border. The internal surface forms the walls and roof of the spinal foramen. This sur- face is smooth,- and more or less arched. In some vertebrse, the walls are more nearly perpendicular and the roof is flatter than in others. The exterr.al surface of the annular portion is rough and consists of two sides and a 14 OSTEOLOGY. crest. The crest is marked b\- an elevation more or less prominent, and called the superior spinous process. The spinous processes of the dorsal vertebraB are united so as to form a continuous ridge. This process, also the inferior spinous process, is for the attachment of muscles, which pass from one vertebra to the other. The anterior border of the annular portion is deeply concave from side to side. The lateral prolongations of this border are called the ante- rior articular processes. Each of these is furnished with a smooth, slightlv convex facet which looks upwards'and in- wards. [The description of the vertebrae given here should be studied with the cervical vertebrae, since they are separ- ated from one another, and for this reason, the description is given more directly concerning them. J The posterior bor- der has three concavities, two lateral, one between each side of the body and the corresponding articular process, and the third above, between the two processes. The posterior articuhu' procfs.ses are furnished with facets which look downwards and outwards. When the vertebrae are in posi- tion, the openings forward bv the concavities in the borders are called intervertebral notches. The processes which come off from the sides of the annular portion of the verte- bras are called transverse processes. .The transverse, as well as the other processes, vary greatly according to the position of the vertebra in the column. The transverse processes of the dorsal- vertebra; are generally consolidated, while the same processes in the cervical vertebrae are rough tubercles, coming ofl" under the anterior articular processes, pierced at the base by a foramen, and sending backwards, parallel with the Iwdy a styloid projection, which varies in length and strength according to the position of the vertebra to , which it belongs. THE SKELETON. I 5 SPECIAL DESCRIPTION OF SOME VERTEBRAE. The Atlas. — This, the first bone of the column, and that to which the head is directly attached, is a thin ring and ea- sily distinguished from any other vertebra in the column. It has no transverse processes, and no anterior articular pro- cesses, save that which marks the body. The Axis. — This is the second cervical vertebra. It presents a well developed odontoid process, under which is a facet for articulation with the body of the atlas. There are no trans^■erse processes ftnd a small groove represents the former which pierces the base of the transverse processes of the succeeding vertebras. The superior spinous pi'ocess is short, thick and blunt. Third and fourth Cervical. — These two resemble each other closely. Their transverse diameter is greater than that of either the preceeding or succeeding vertebriE. The expansion is on the sides of annulur portion and is pierced by a vertical foramen — one on each side. Both have trans- verse processes with short styloid prolongations. The supe- rior spinous process of the third, points backwards, while that of the fourth points more directly upwards, and that of the fifth points slightly forwards. Beyond the fourth cervical, the vertebras increase in length, the styloid projections from the transverse processes, become longer and more pointed, and the posterior articular processes are long and diverging until the eighth or ninth cervical is readied. Beyond these the vertebrae decrease in length and increase in thickness to the dorsal. In the last cervical, the transverse process is but an arch enclosing a larger foramen. In the last three cervical and the first dorsal, the inferior spinous process is 1 6 OSTEOLOGY. well developed and is inclined forwards. The change from the cervical to the dorsal, can at once be recognized by the absence of the foramen which pierces the base of the trans- verse process in the cervical. This foramen is very large in the last cervical, but absent in the dorsal. In the latter, there is a foramen along each side of the vertebrse but this foi'amen is formed by the ribs, each of which unites with its vertebra in two places. The first and last dorsal can gen- erally be separated from the others. But the superior spi- nous processes, the bodies, transverse processes and often the inferior spinous processes of the other five have grown together so completely as to form one bone. The lumbar and sacral vertebrae are united to one another and to the bones of the pelvis. But the line of union be- tween the bones of the pelvis and these vertebrae is generally quite distinct. The coccygeal vertebras are movable upon one another. They are seven in number and are easily recognized from those of the other regions. The first one is united with the sacral. It has broad transvers processes and a long arch enclosing a foramen, represents the superior spinous process. None of the coccygeal vertebras have the inferior spinous process. The succeeding five vertebra have well developed trans- verse processes, those of the second being the broadest and those of the fifth and sixth being the longest. These trans- verse processes are smooth, thin and slope downwards. These veitebrse also have prominent superior spinous pro- cesses, which are bifid, pierced at the base by a foramen and decrease in size from before backwards. The seventh coccygeal, or last bone of the column is quite THE SKELETON. I 7 different from any other vertebra. Fi-om its peculiar shape,' it is known as the plough-share bone. It is long, turned upwards and comes to a point at its posterior extremity. Anteriorly on its superior edge, there are two short protu- berances, which represent the bifid superior spinous pro- cesses of the preceding five coccygeal vertebrs. It has no transverse processes. Its inferior edge is rough, convex longitudinally, and is marked toward its anterior end by a medium groove. This bone is formed by the union of two or more bones. It supports the oil-glands and gives at- tachment to the quill feathers of the tail. It is entered an- teriorly by the termination of the sjjinal foramen. THE STERNUM— BREAST BONE. This bone forms the floor of the abdominal cavity, and supports the viscera. The general form of its interior or upper face is concave ; while the general shape of its ex- ternal or lower face is convex, both latterally and longi- tudinally. We shall consider this bone as consisting of a body and eight processes. The body is the thick, strong part of the bone, from which the processes pass out. It constitutes the anterior part of the bone, and presents for study two faces with their borders. Projecting from the mid- dle potnt of the anterior border of the body, is a short, thin process, which is pierced at its base by foramen. This pro- cess is the manubrium. On each side of the base of this pro- cess, is the facet for the articulation of the coracoid bones with the sternum. These facets aie convex from side to side, and concave from above downwards. The two facets joittj forming the foramen, which pierces the base i8 OSTEOIX)GY. of the manubrium, so that the two form a depression along the entire anterior border of the body. Direct- ly over tlie extrem'ities of this depression arise the an- terior costal processes, which extend forward and upward. ,, „ These processes present Fig. 3. — Sternum. ^ ^ two faces, an internal and an external, and two edges, a SLiperior and an inferior. About half way up the miner face is a small pi^otuberance, from which the surface slants, both towards the base and towards the extremity of the process. The exter- nal surface is slightly concave and more or less marked by lines passing from the superior edge forward and across to the inferior edge. The infe- rior edge is smooth and concave, the superior more or less rough and convex. From the base I. Manubrium. 2. Anterior Costal Process, of'the anterior COStal pro- 3. Posterior Costal Process. 4. Lateral Pro- cess. 5. Body. 6. Posterior or Keel-hearing CeSS backwards, the bor- P™"^>'- der of the body is called the costal border, and is occupied by the facets for the articulation of the sternal ribs. Sometimes one of the facets lies up on the posterior edge of the anterior costal THE SKELETON. I9 process. At the posterior extremity of the costal border, the lateral process extends backwards nearly parallel with the posterior process, which bears the keel. From the superior edge of the base of the lateral process, arises the posterior costal process, which extends upwards, backwards and outwards. The faces and edges of the posterior cos- tal processes are smooth and even. At its extremity this pro- cess spreads out fan-shaped, and is thin. The long lateral process — one on each side of the posterior process — extends backwards and slightly upwards. Its length is about five- sixths of that of the posterior process, its inner face is smooth, its outer, convex from side to side. Near its ex- tremity there is a slight protuberance on the superior edge of this process. From the base of the lateral process to the base of the posterior or keel-bearing process, the margin of the body is thin and often pierced by one or more very small foramina. The posterior or keel-bearing process is the largest and most prominent part of the bone. It arises from the middle of the posterior margin of the body, and extends backwards and slightly upwards. The internal or superior face of this process forms a smooth, shallow trough, which slopes from the posterior extremity to the base of the pro- cess. Just at the base will often be found a small foramen. The external or inferior face, is convex both laterally and longitudinally, and is mostly taken up by the keel, which arises from its median line. The keel is the promi- nent part of the bone, projects downward, and serves for the attachment of the pectoral muscles. It gradually de- creases in prominence from the base to the extremity of the process. It presents two faces, both latei'al, one edge, the inferior and one end, the anterior. The faces are smooth 20 OSTEOLOGY. and even, The edge is rough and thick anteri'.'rly, smnoth and thin posteriorly. The edge is seldom or never straight, as the bone has been pressed to the one side or the other somewhere along its margin. Anteriorly the origin of the keel is shown on the under surface of the body by two eminences with a depression between. These pass back- wards and downwards (holding the bone in its natural po- sition), then unite and pass forward anil downward, so as to form a beak to the most prominent portion of the keel. THE CORACOID. These bones lie behind the clavicle. Tliey rest upon the sternum and form the chief support for the shoulder. They join the sternum in the two facets which mark the anterior border of the body of that bone, and which unite to form the foramen piercing the base of the manubrium. From the .sternum, these bones pass forward and upward, being artic- ulated above with the scapula, humerus and clavicle. The anterior or external face of tlie curacoid is stningly convex and increases in width toward its sternal extremity. Its posterior or internal face is rough and slightly concave to- ward the sternal extremity. The articular facet on the ante- rior border of tne body of the sternum, into which the lower extremity of the coracoid fits, is convex from side to side and consequently there is a depression in the end of the con- coid bone, corresponding to the convexity in the facet. This depression is not median, but much nearer the inner edge of the bone, the internal projection being smaller and shorter than the external. The internal projection passes into the forameti under the menubrium, where it meets the corres- THE SKELETON. 21 ponding projection of ihe other conicoid. The external pro- jection is large and extends out even beyond the limit of the Fig. 4. — Sternum and Bonks of Scapular Arch. facet and partly covers the external face of the anterior cos- tal process. The upper extremity of the coracoid is quite irregular. The scapula passes along almost parallel with 22 OSTEOLOGY. the vertebral column and articulates with the posterior or internal face of the coracoid. The scapula, thus acts as a brace, not allowing the upper extremity of the coracoid to be forced backward too far. The extremity of the scapula which fits against the coracoid, bears a median depression into which the coracoid sinks, and two p.iojections — one on each side of the depression. The external projection is short, large and forms about one-third of the facet for the ar- ticulation of the humerus : the other two-thirds of the facet being formed on the outer edge of the coracoid. Above the facet for the humerus, the coracoid terminates in a protuber- ance which bends inwards coming directly over the internal projection of the extremity of the scapula, to which it is joined by a strong ligament. A notch, or with the ligament a foramen, is thus formed. The floor of this notch or for- amen is smooth, and over this passes the long, strong tendon of the pectoralis minor to be inserted into the hti- mei'us. The clavicle is attached by a ligament to the point of this extremity of the coracoid. On the anterior face Of the coracoid just above the facet for the humerus is a de- pression formed between the rough and raised border of the facet and the protuJDerance which bends inwards. There is also a slight depression on the end of this protuberance arid the end of the clavicle fits into this depression. i THE g'CAPUt'A. This is a long, thin bone, which lies almost parallel with, and about an inch from the dorsal vertebrae. It rests upon the ribs and terminates anteriorly against the coracoid. Its posterior extremity is flat and narrow, but never terminates THE SKELETON. 23 in a point. Its anterior half or two-thirds is thick and strong. Its superior edge is thici< anteriorly, thin posteriorly. Fig. 5. — Bones of Scafular .\itcir. 2. Coracoid. 3, Ilunienis, ■ 4. Scapula. and strongly convex. From the anterior extremity of the bone, the superior edge passes back in almost a straight line, for about two-thirds the length of the' bone ; it then turns downwards. The inferior edge is smooth and concave. The posterior part of the bone is bent not only strongly downwards, but slightly outwards. The anterior extremity, as has been mentioned in describing the coracoid, bears a median depression and two lateral projections. The exter- nal projection assists in forming the glenoid cavity, while the external passes behind the coracoid and is attached by a ligament to the clavicle thus forming the foramen triosseum. The three bones, coracoid, 'Clavicle and scapula form a strong support for the arm. The coracoid, the strongest of the three, acts as the direct support. The scapula prevents the displacement of the coracoid in an anterio-posterior direc- 34 OSTEOLOGY. tion, while the chivicle hinders the displacement of the cora- coid liiterallv. THE CLAVICLES. These bones are united inferiorly, forming the "wish- bone" or "merry-thought." From the point of union, a short, thin, wid;, process extends backwards towards the sternum, hut is not attaclied to that bone only ligamentously. Fie. 6. Clavicles. This short process presents two faces, lateral, and -a border, which is thin above and thick below. The pi'ocess is often almost circular. From this pro- cess, the clavicles pass, at first, forward and upwards, then almost directl}' up- wards to the corresponding extremities of the caracoid. Through the greater part of their length, these bones are smooth, and a transverse section would be nearly circular. The upper extrem- tremtty of each clavicle is, flattened out somewhat, so as to ofier two faces, an external and an inter- nal. The external, face is smooth and slightly concave ; the internal smooth and slightly convex. These bones are the most variable of the bones of the scapular arch. In the tame goose the clavicles are united, but do not send back a , process from the point of confluence as in the chicken ; while from the point of union, they extend first forward and downward, then upward and backward. The clavicles of the goose are much broad- er and stronger than those of the chicken. In the lat- THE SKELETON. ^5 ter the shape of the " wish-bone " or two clavicles united is that of the letter V, while in the former the form more nearly resembles that of the letter U. In the goose the ex- tremities of the clavicles are not widened, but terminate in points : while about one-third of the distance from the point to the union, there is a small protuberance on the anterior «dgre of each clavicle. ANTERIOR EXTREMITIES. The bones of the anterior extremities will be considered In order from the shoulder to the fingers, or from the prox- imal to the distal extremity. This region may be regarded as consisting of three parts, the arm, the forearm, and the hand. There is only one bone, the humerus, belonging to the arm. The forearm contains two bones, the radius and the ulna. The skeleton of the hand consists of the carpal bones, two in number, of the metacarpal, three, and of the phalanges or bones of the fingers. THE HUMERUS. This, the first bone of the wing is especially characterized by the form of its extremities. The side of the bone next to the body is called the " anconal" side while the opposite one is called the " palmar. " Besides these faces, the side or border corresponding with the position of the radius, is called the radial side or border, and the one corresponding with the ulna is called the ulnar side or border. The two extremities of the bone are slightly inclined forward, so that the general shape of the ulnar side is concave. The radial face is nearly straight along the upper two-thirds 3 36 OSTEOLOGY. the length of the bone, but is slightly concave in the lower third. The shaft is smooth, and a transverse section of it Fig. 7.— Humerus. would be sub-eliptical. The ends of the bone are expanded, the proximal being the broader of the two. The palmar face of the proximal end is mark- ed along the radial side by the superior crest, which affords an eminence for the insertion of the broad tendon of the great pecto- ral . muscle. Directly in front of this crest, is a Anterior view. Posterior view, small depression, along which the long head of the biceps passes, and which is called the bicipital fossa. From this fossa across to the ulnar side, the palmar face is smooth, convex and extends out over the inferior crest. It is along this smooth, convex- extended sui"- face that tiie short head of the biceps takes its origin. The anconal face of the upper extremity is rough ; its most no- ticeable feature being a foramen which passes into the inte- rior of the bone. This foramen is known as the Foramen Pneumaticum of the Humerus. Above and along the ulnar border of this foramen is a crest, the inferior crest. It serves for the insertion of several muscles. The extreme proxi- mal end of the humerus is a smooth, rounded or semi-oval convexity, the transverse diameter of which is the longer. It fits loosely into the glenoid cavity, being attached by liga- ments. It is not separated from the rest of the bone by a THE SKELETON. 27 neck or constriction. The entire proximal extremity of this bone bends downwards and inwards. The distal extrem- ity presents on the palmar face, two articular surfaces, and a small sub-triangular concavity above them. The two ar- tieular surfaces are convex and the radial is the larger of the two. The radial articular surface arises about the middle of the bone, in the sub-triangular concavity and passes ob- liquely to the radial corner. There is a slight depression between this articular surface and the next or ulnar one, which lies farther toward the ulnar side and does not extend so far up into the concavity as the preceding one. Beyond the ulnar condyle there is a thii'd eminence, but this one projects on the anconal face of , the bone. On the anco- nal face there is another eminence. It is much smaller than the preceding and seems to be a continuation of the ra- dial condyle. Between these two eminences on the anco- nal face, is a smooth, shallow depression in which the olecranon process of the ulna moves. THE ANTIBRACHIUM. Tlie forearm consists of two bones, the radius arid the ulna. The ulna is much the larger and stronger of the two. The position of the ulna with respect to the radius, is posterior in the expanded wing, and exterior when the wing is folded. The bones are attached to each other at the two extremities in such a manner as to allow but little or no rotation. This is necessary, in order to give great firmness and power of resistance to this part of -the wing during flight. The forearm is equal, or nearly so, in length, with the arm, so that when the wing is flexed, the distal ex- zS OSTEOLOGY. ticmity of the antibrachium lies near the proximal end of tlie l)rachinm. Along the middle part of the antibrachium its two bones curve from each otb.er, the ulna being curved to a much greater extent than the radius. The ulna is some longer than the radius. When in the natural position, the proximal end of the ulna projects considerably beyond the proximal end of the radius, while the distal end of the ra- dius projects slightly beyond the corresponding extremity of the ulna. THE Forearm THE ULNA. The upper extremity of the ulna is drawn into a short protuberance, the olecranon process. It will be convenient to consider the ulna as presenting two faces and as many edges. The faces will be distinguished as anterior and post- PiG. y. — Bones of erior ; the edges as radial and external. The external edge, a prolongation of the proximal end of which forms the olecranon process, marks the greatest convexity of the bone longitudinally. The radial lies directly opposite the external edge, and marks the greatest concavity of the bone longitudinally. The radial edge leaves the proximal end of the ulna, where that bone artic- ulates with the radius, and becomes less distinct as it approaches the distal end. The anterior face is slightly con- cave longitudinally ; near the proximal end it is almost flat laterally, but near the distal end it is strongly convex laterally. The posterior face "is slightly Ulna, 2. Radius. THE SKELETON. 39 convex longitudinally, and strongly convex laterally. Be- sides the olecranon process, already mentioned, the proxi- mal end of the ulna bears, towards its anterior face, a semi-lunar depression which fits upon the ulnar tuberosi- ty of the humerus, and towards its posterior face, a small- er facet which glides upon the radial tuberosity of the hu- merus, when the wing is strongly flexed. The eminence bordering the smaller facet is the most prominent part of the proximal end of the bone. Just on the border of these facets and where the radial edge first appears, is a small shallow jfacet in which the head of the radius lies. The distal end of the ulna presents, towards its anterior face, a rough protuberance which points upwards and terminates in two points ; towards its posterior face, a thick rounded' protuber- ance which bends slightly downwards and backwards. The depression between these two protuberances is concave lat^ erally and convex vertically. ' THE RADIUS. The .sha,ft of the radius is sub-cylindrical near the proxi- mal end ; but flattened toward the distal end. The proxi- mal end is marked by a circular depression, which moves upon the radial tuberosity of the humerus^when the wing is, flexed. On the ulnar side, the border of this depression is flattened, so that the head of the radius lies .upon the ulna and is securely attached to that bone. ' Toward the distal end, the radius is slightly curved, the anterior, aspect being concave. The distal end is the widest part of the bone and lies on its edge in the median depression of the correspond- ing extremity of the ulna, and with its anterior face against 3° OSTEOLOGY. the posterior side of the upward-projecting protuberance of the uhia. This extremity of the radius projects a little be- 3'ond the ulna. THE HAND. In describing the hand of birds, Owen says : " The bones Fig. 9. — Bones of the hand are developed in length, but OF Fore-arm and contracted in breadth. The wedge-like Hand. (After . , . , . Huxley ) adjustment of the free carpalh is such as to restrict the movements of the hand upon the arm to abduction and adduction, or flexion in the ulno-radial plane, requi- site for the outspreading and folding up of the wing. The hand of the bird moves thus in a state of pronation, without the power of rotation, or of proper flexion or extension, i. e. in the anco-palmar direc- tion ; so that the \\ing strikes tirmlv. and with the full force of the depres-^or nui>- cles upon the air." The large feathers which cover the liand, arc called the ''primaries;" those which belong to the fore-arm are called the " secondaries ; " while those of the arm are called the '■ scapularies. " The bunch of feathers attached to the index finger form the '-spurious" or "bastard'' nuhiris. s. First pha- wing. The ofiice of prehension for which lanx of middle finsfur. ., 1 i 1 ,. 9. Second phalanx of ^^e coniplex hand ot man is ,m. well middle tinker. Suited, is, ill birds, filled by the beak. Consequently the capability of the great variety of motions I. VliY.i. 2 Riidius. 3. l'ln;ii-c:ii-]i,il, 4 R.i- dial carp.ij 5. Index finger. 6. 'J'hird ineta- carpid. 7. I)iLj;itus an.- THE SKELETON. 3 1 necessary to an organ of prehensiou, is tranferred from the liand to the neck. In birds of flight the length of the fore- arm and hand is greater than in gallinaceous birds. CARPAL BONES. The carpal bones are two in number and are designated by the names "radial" and " ulnar.*^" The radial carpal presents three articular surfaces. The facet for the radius is deep ; but does not extend across the full width of the bone. Just opposite this facet is another for articulation with the metacarpal. This one is beveled at the expense of the inner side of the bone. On the posterior border of the bone, there is a small facet which serves for articulation with the radial edge of the distal end of the" uTna. The supe- rior face of the bone is marked by a longitudinal groove. The remaining surface of the bone is somewh:it irregular in or- der to better serve for muscular attachment. Since CoueS' description of the second or ulnar carpal of the Colvmbus Torquatus, suits equally well for the same bone in the fowl it is here copied in full. " The second smaller bone of the car- pus, which represents the second row of carpal bones, is placed just in the bend of the joint on the ulnar side, wedged in between the ulna and metacarpus, witli both of which it articulates. Its ulnar aspect presents a smooth, oval, some- what depressed facet, which plays against the extremity of the large articulating surface of the ulna. Its metacarpal aspect presents a very deep horizontal no'ch or fissure, into which is received the inferior ihin border of the metacarpal bone. In flexion and extension of the metacarpus, this small bone rides backwards and forwards along the edge of the 32 OSTEOLOGY. metacarpal bone, being, as it were, astride of the latter^ The non-articular aspects of the bone are rough for the at-f tachment of tendons." The radial carpal corresponds to the first row of carpals, or to the scaphoid, semilunar, and cun-j iform in the hand of man. The carpals of the hand of the goose differ but little, only in size, from those of the chick- dn. The size of the two carpals is about the same in the chicken ; while the radial carpal is much the larger in soma birds. THK METACARPUS. The metacarpus consists of three bones which are firmly grown together. The ladial metacarpus is the smallest and appeals as an enlargement or process, belonging to the proximal entl of the large middle metacarpal. The proxi- mal end of the radial metacarpal is prominently elevated and serves for mu:-cular ;ittachments ; while its distal end lies close to the middle metacarpal, and supports the index finger. The middle metacarpal or the " medius, " is the larg- est of tjic three. Its proximal end articulates with the two cijpals ; ^vhile its distal end supports the middle finger. The third metacarpal is bent so that while each of its ex- tremities is anchylosed with the corresponding extremity of the " medius," the bodies of the two bones are separated by a space about one-fourth of an inch wide. The proxi- mal end of, the third metacarpal articulates with the ulnar carpal ; while its distal end supports a digit which corres- ponds lo the digitus annularis, or ring finger. In the hand of the goose, the third metacarpal is not bent so much as in the hand of the chicken ; and consequently the space be- THE SKELETON. tween the second and third metacarpal is not so wide in the hand of the goose as in that of the chicken. THE PHALANGES. The index finger consists of two phalanges. The proxi- mal phalanx of this finger is from one-half to three-fourths of an inch in length, rough and trihedral. Its radial aspect is marked by a sharp, prominent ridge. This phalanx is movably articulated with the first or radial metacarpal bone. The second phalanx of this finger is only a small pointed spicula of bone, about one-foUrth of an inch in length. Most of authors represent this finger as having but one phalanx ; but if care be taken not to lose any of the parts in masceration, two phalanges will certainly be found in this finger both for the chicken and the goose. Some au- thors call this finger the pollex, or thumb ; while others call it the index finger ; but most authors agree in describing this as consisting of but one phalanx. A careful examina- tion will show that there are two in some vai'ieties of the domestic fowl, at least, if not in all. The middle phalanx also consists of two phalanges. The proximal phalanx of this finger is thick along its radial side ; but much expanded and thin along the ulnar side. The lamelloid expansion of this phalanx is excavated for the attachment of the primaries. The second phalanx of this finger is trihedral and terminates in a point. Its radial side. is thick ; while a sharp, prominent ridge marks its ulnar aspect. According to Coues, this finger in the Colymbus Torquatus consists of three phalanges ; the third phalanx being a very small, insignificant, acutely pointed spicula of 34 OSTEOLOGY. bone, scarcely a thirrl of an inch long. The digitus annu- laris consists of one phalanx. It is about one-half an inch long, and lies along the border of the expansion of the first phalanx of the middle finger. BONES OF THE PELVIS. The pelvis consists of three bones, the ilium, ischium and pubis. These three bones are firmly united, forming a pair of strong, large irregular bones. 1. Ilium, 3, Pubis, 5 Consolidated Dorsal Sjiine, 2, Ischium, 4. L'audal\"ei"tubru, 6. Ribs, The ilium is remarkable for its length. Anteriorly it ex- tends o\er the last dorsal, and posteriorly it terminates upon a line with the fifth coccygeal vertebra. Its superior edge with the exception of a short distance at its posterior ex- tremity,. is firmly united to the vertebral column. Anteri- orly this edge is united to the spinous processes, which here are consolidated, and the transverse processes extend out- THE SKELETON. 35 ward against the slanting ilium. In thi§ way a foramen is formed on each side of the consolidated spinous processes. The roof and external wall of this foramen is formed by the ilium. The floor is formed by the transverse, and the in- ternal wall by the spinous processes. The inferior edge of iliuiTl along its anterior part, is free, then forms a part of the the acetabulum, next forms the superior boundary of the sci- atic foramen, and posterior to this, is united with the ischium. The superior fiice of the ilium in front of the acetabulum, slants forwards and downwards. This forms an extensive surface for the attachment of the glutsei and other mirscles. The iliac border of the acetabulum is rough, and promi- nent, its most prominent point being next to the sciatic foramen. Here tlie border extends up so as to forrn a protuberance, which is grooved upon its acetabular side. This protuberance fits against the internal side of the gr^at trochanter of the femur, has a rounded convex border, and is called the antitrochanter surface. Directly over this protuberance, the bone is slightly depressed, and above the depression is raised again. Over the sciatic fora- men, the superior face of the ilium is broad and but slight- ly ponvex. Posteriorly it terminates in a point, which is directed upwards. Back of the sciatic foramen, there is a marked protuberance, which points out over the ischium. The internal or inferior face is even more irregular than the superior. Anteriorly it is rough and convex from side to side. But more posteriorly and in the region of the aceta- bulum and sciatic foramen, it is hollowed out deeply.. This depression extends back as a pocket even beyond the last sacral vertebra. The ischium is narrow and thick at its anterior end, 36 OSTEOLOGY. where it forms the back part of the acetalmhim. Beyond this, it forms the inferior border of the sciatic foramen and still more posteriori}' its internal or superior border is joined to the inferior or external border of the ilium. Its posterior border slopes downwards and backwards. Its inferior bor- der is thick and passes from the acetabulum backwards to the posterior point of the bone. The shape of the ischium is triangular, narrow anteriorly, and widening posteriorly. Its external face is smooth, but has a slijihtly raised border. Its internal face has a ridge passing longitudinally and al- most parallel with the inferior border. The pubis is a small slender bone lying along the inferior border of the ischium, with -which it is imited b\' fibrous tissue. Anteriorly the pubis forms the lower part of the acetabulum' where it is joined to both the iHum and is'chiuni. From the acetabulum, it passes backward and touches the ischium again forming the foramen ovale. Beyond this, it has no osseous connection with the ischium, but passes be- yond the posterior extremity of that bone, then turns up- wards and more in towards the bone of the other side. FEMUR. The shaft of tiie femur is cylindrical, curyed forwards strongly, outwards slightly, and presents the appearance of having been twisted. The' extremities are well mai'ked, presenting many characteristic features. Projecting from the upper extremity is a short protuberance, with its axis almost at right angles with that of the shaft. This protuber- ance bears the head, which is hemispherical and fits into the acetabulum. The head is more or less rouph for THE SKELETON. 37 Fig. 1 1.- Femur, the insertion of the ligamentum terreS Tibia AND Fibula, which fastens the 'femur securely to the body. Below the head, the protuberance is slightly constricted, forming the neck. Opposite the head on the external side, the bone is rough, thick, extends upwards and slightly inwards, forming the great troch- anter. The space between the head and trochanter is smooth, and forms a firm support for the body. The lower extremity of the femur has two prominent condyles, internal and external, and a deep median fossa. The fossa is concave laterally and convex longitadinally The internal con- dyle, the smaller of the two, presents a smooth convex border, narrower above, wider below. The external condyle ex- tends further down than the internal. Pos- teriorly, the external condyle is divided by a slight depression. Of these two parts the internal is the larger, and belongs to the tibia, while the depression and outer part fit upon the head of the fibula. The patella, which is a small irregular bone, lies in the intercond\'lar fossa. Its inferior surface is strongl}- convex. Each side of this convexity is a smooth face, which fits against and moves along the in- ternal face of the corresponding condyle. The patella is bound by strong, wide liga- I. Femur. 2. Ti])ia 3. Fibula. ments, to the femur. 38 OSTEOLOGY. TIBIA. This is the longest bone of die body. It is slightly curved, so that the two extremities and the middle point project far- ther forward than the interrnediate points. The shaft is cyl- indrical near the middle point, but increases in its transverse diameter toward its extremities. The upper extremity is broad, presenting an extended surface for the femur to I'est upon. It has two depressions, an internal and an external. The internal is shallow, regular, receives the inner condyle of the feiiiur and is called the " entocondylar " surface. Posteriorly to the entocondylar surface, the bone is smooth and projects backwards over the shaft. The external or " ectocondylar " surface, which receives the external condyle of the femur is rough and slants outwards, being much deeper than the internal. The ridge dividing these two sur- faces, is called the " intercondylar " convexity. Posterior to the ectocondylar surface, is a small hemispherical protuber- ance, to which the fibula is united by ligaments. Anterior to these articular surfaces, there is a crest which rises above them and is extended transverselv. The posterior face of this crest is rough and conforms \\i{h the surfaces, already described, in general shape. The anterior face of the crest is marked by a thin, prominent, crooked ridge. This ridge fonr^s tlie most prominent feature of the upper extremity of the bone, occupying its anterior aspect. The ridge pre- sents two sides and an edge. The external or fibular side is smooth and concave in both directions ; the internal side is smooth and convex. The edge is thin and convex. The ridge corresponds with the intercondylar convexity which lies on the posterior side of the crest and has already been THE SKELETON. 39 described. On the external, or fibular side of the bone, the crest projects out further than the main portion of the head and terminates in a thickened point. The lower extremity of the tibia bears two prominent, smooth condyles, with a deep median fossa. These condyles are developed from be- hind forwards, being more prominent anteriorly than post- eriorly. On the anterior face of the bone, these condyles be- gin as ridges about an inch from the distal end of the bone ; while on the posterior face, they do not extend up half so far. Anteriorly, the median groove is deep and is often crossed by ligaments which are found ossified in the old subject. The internal condyle is the more prominent of the two. FIBULA. The fibula is a small bone situated along the external side of the tibia, and attached to that bone. It becomes smaller from above downwards, terminating in a point about four-fifths the distance down the tibia.. Its head is compressed laterally and points backwards, being convex along its longer axis. The internal or tibial side of the head is smooth and slightly concave, while the external is convex. It is attached to the tibia, for about one-third its length, this distance being well marked on both bones ; being shown on the tibia by a ridge, which suddenly termi- nates at the point of severance. TARSO-METATARSUS. The upper extremity of this bone, like that of the tibia, has two articular surfaces, the •' entocondylar" and the "ec- 40 OSTEOLOGY. tocondylar. " The entocondylar is the deeper, having a more prominent border than the other. The space between these surfaces is called the intercondylar space. From the interior part of this intercondylar space, rises a small protuberance, which acts as a brace while the bird is roosting. On the posterior aspect of the proximal end, there is a prominent elevation, which is subdivided by a shallow groove, and which is pierced by a canal. , This pro- tuberance, or these protuberances, is called " calcaneal, " and the grooves serve for the passage of the tendons of some of the muscles. The anterior aspect of the bone towards the proxiinal end, bears a longitudinal depression. This de- pression is nearer the inner side, and is deepest directly un- der the head, and gradually becomes less distinct until it disappears near the " spur." The spur is a strong projec- tion which points inwards, coming ofl" from the tarso-meta- tarsus, down about two-thirds its length. Often there is a second riidimantary spur. The posterior asjDect of the bone near the spur presents a slight, longitudinal grove, along which tendons pass. Below the " spur" the bone becomes thinner and wider, terminating in three condyles, separated from one another by two " fore-and-aft" grooves. These condyles serve for the attachment of the second, third, and fourth toes. The inner condyle, one for the second toe, is smooth, hemispherical in shape, and does not bear a groove. The middle condyle, the one for the third toe, is the longest of the three, and bears a median groove, concave laterally-, convex longitudinally. The outer cond3'le, one for the fourth toe, is about equal to the internal in size, but it bears a groove similar to that on the middle condyle. The first toe is attached to the tarso-metatarsus by ligaments only. It THE SKELETON. 41 comes off a little above the level of the other three — be- tween the "spur" and the second toe, but much nearer the toe, and projects backwards and inwards. Owen names the bone which has been here described as tarso-metatarsus as metatarse, but the name of tarso-metatarsus is the one most generall}' used. THE TOES. Tlie toes are four in number. Three of these project for- wards, while the other projects inwards towards the oppo- site leg, and sliglitly back- p^. 12.— The Foot. wards. The first three may be knovVn as the anterior, and the other as the posterior. The posterior one corres- ponds to the "hallux" or great toe. . Tlie others are, from the hallux outward, second, third and fourth. The fifth toe is entirely wanting. The third toe is the longest, and the first. or "hallux" is the shortest. The second and foiu'th toes come off from the metatarsus on the same level, the third comes off lower than the sec- ond and fourth. The meta- tarsal of the first toe is separate from the tarso-metatarsal bone, and arises above the union of the three protuber- 4 1 . Posterior toe. 2. Second toe. 3. Third toe. 4. Fourth toe. y TEirso-motiitarsus. 42 OSTEOLOGY. ances, which mark the distal end of the tarso-metatarsus. The first toe has two phalanges ; the second three ; the third four ; and the fourth five. The pro.ximal end of the pha- langes is called the basis, and the distal end the capitulum. The basis has a horizontal depression, ov fossa articidaris transversa. The superior border of this fossa is called the tuberculutn superhis, and the inferior border the tubercu- lum inferuis. The capitulum consists of two lateral condyles and a median vertical groove or sulcus longitudi- nalis. The motion of the phalanges is limited to one direc- tion. In the embryo, at first, the toes are all of the same length ; but soon the anterior toe ceases to increase in length as the others do. The distal phalanx of each toe is pointed and curved to correspond with the claw. The body or middle part of the phalanges is smaller than the extremities. The inferior surface of the body is curved upwards, so that on this side, the bone is concave longitudinally. The upper and lateral aspects of the bone are smooth and even- ly rounded. THE RIBS. In the domestic fowl there are seven pairs of ribs ; in the duck there are nine pairs ; and in the red-tailed hawk there are eight pairs. In birds in general, the number of pairs of ribs varies from six to twelve. Each true rib consists of three parts, the dorsal part, the sternal part, and the hamu- lus costalis or processus uncinatus. The false ribs may consist of one, or of two parts ; but never of three. The false rib may be, and generally is, only the dorsal part, or the dorsal part with the processus uncinatus ; while in some THE SKELETON. 43 cases the sternal part only will be found, and will constitute the false rib. In the fowl, there ai-e two pairs of false, and five of true ribs. The false ribs are the first two pairs. The first pair generally consists of the dorsal part only ; and the second pair consists of the dorsal part with a short process. The three parts of the true rib are united with one anoth- er, with the vertebja and with the breast bone. The dorsal part of the rib is wide and has sharp edges. Each rib unites with the vertebral column in two places. The two branches, at the pro\imal end of the ribs, are known as the Capittilum and the Tuberculuni. The Capi- tulum. articulates with the body of the vertebra ; but not with two vertebrje, as is the case in man and other mammals. The Tuberculum articulates with the transverse process of the same vertebra, with which the Capitulum articulates. The space between the Capitulum and the transverse pro- cess, corresponds to the foramen which ' pierces the base of the transverse process in the cervical vertebrae. From the vertebral column, the anterior ribs, or the anterior dorsal ribs, extend downward and backward ; while the posterior ones extend downwards and forward, to terminate against the extremities of the sternal ribs. From the posterior edge of the lower third of the dorsal rib, a process, the hamulus costalis, is given off. It is thin and of nearly the same width as the rib. It passes upward and backward over the succeeding rib. This process is de- veloped as a separate bone ; but in the domestic fowl, and indeed in most of birds, soon becomes completely fused with the dorsal rib. In some rare instances, the union is not complete ; but by means of ligaments. These process- 44 OSTEOLOGY. es give additional strength to the ribs, and according tO' Selenlca, are very long and strong in birds of prey ; but short and vs'eak in the iiatatorcs. The sternal ribs are at- tached to the sternum at one extremity, and to the dorsal ribs at the other extremity. The sternal end is furnished v\'ith two tubercles, which fit into facets along the costal bor- der of the sternum. This attachment is by means of a lig- amentum cafsulare. The superior extremity of the sternal rib is attached to the inferior extremity of the dorsal rib, b3' means of a ligament. Selenka gives the ligaments of the ribs as follows : "The principal ligaments are, a ligament- iim capsalai-c, which binds the head df the rib to the body of the vertebra; the !ig. traiisversum cxternuin^ between the tubercle of the rib and the transverse process ; the lig. triangulares 'which connects each proc. uncinatus with the posterior edge of the corresponding rib ; and a ]ig. cap- stilare which binds the ends of the dorsal ribs to the sternal ribs. The sternal end of the sternal ribs is attached to the sternum by a lig. capsulare. " The doi'sal part of the last j^air of ribs is often united with the ilium, and the sternal part of the last two pairs is covered by the expanded ex- tremity of the posterior costal process. The processus u-iicinattis is, of course, wanting in the last pair of ribs. BONES OF THE HEAD. There are twenty-nine bones belonging to the head. This number does not include the hyoid bone, which may be considered as belonging to this region. Of these twen- ty-nine bones, five are single, and twenty four are in pairs. THE SKELETON. 45 The single bones are, the occipital, basisphenoid, orbitosphen- oid, vomer and inferior maxilla- fjq i3._The Skull. ry. The bones in pairs are, the parietals, temporals, alisphenoids, tympanies, pterygoids, frontals, nasals, premaxillaries, maxillaiies, lachrymals, malars, and palatines. The bones of the head may be di- vided into two classes, those of the skull and those of the face. The bones of the skull are fifteen in number, three single, and twelve i. Temporal. 5. iup. maxihiry. m pairs. The single bones of the ^ ,f„i„ ^ ocdptoi. skull are, the occipital, the basi- 4 i'r«^ Maxiiii.iry. sphenoid, and orbito-sphenoid. The bones of the skull, in pairs, are parietals, temporals, frontals, alisphenoids, tympa- nies, and pterygoids. The bones of the face are fourteen in number, two single and twelve in pairs. The single bones of the face are the vomer and inferior maxilhn-y. The bones of the face in pairs are, the malars, pahitines. pre- maxillaries, nasals, maxillaries and lachrymals. Since the bones of the skull are so closely united, it will be well to examine it first as a whole, and to notice some of the most prominent features, by means of which the position of some of the bones can be determined. The posterior aspect of the skull is semi-circular in shape, with the prominent arch- ed occipital ridge for the border. This aspect is occupied by the occipital bone. It is pierced by a large opening, the foramen magnum- As will be described more fully here- after, the occipital is developed from four bones, the basi- occipital, two exoccipitals, and the supraoccipital. The 46 OSTEOLOGY. supraoccipital forms the superior, the exoccipital the later- al, and the basioccipital the inferior margin of the foramen magnum. The condyle on the inferior border of the fora- men magnum is known as the occipital condyle, and serves to articulate the skull to the vertebral column. It fits into the depression in the body or anterior arch of the atlas. The superior aspect of the head is strongly convex, both longitudinally and laterally. It is bounded posteriorly b}' the occipital ridge, and anteriorly it tei'minates in a point at the distal extremity of the beak. Just in front of the occip- ital ridge, lie the parietal bones, which unite with each other on the median line, and extend down on each side, resting on the temporal bones. The position of the temporal may be known by its zygomatic process, which projects forwards and downwards, and generally unites with the distal end of the post-orbital process, from the alisphenoid. The parie- tals are about one-fourth of an inch wide. In front of the parietals, are the frontals, which extend forward between the orbits and terminate about one-fourth of an inch behind the posterior border of the opening for the nares. At each external anterior corner of the frontals, there is anchylosed a small bone, which projects outwards, forming an antor- bital process, and which sends from the anterior part of its inferior surfiice, a process down towards the malar. This small bone corresponds to the lachrymal bone in the human skull. Anteriorly to the frontals, the nasal branches of the premaxi!lai-y extend forwards, forming the superior border of the osseous boundary for the nares ; while the nasals bifurcate, and the descending branch forms the posterior border of the same opening. The lateral aspect of the head is mostly taken up by the orbital space. The orbito- THE SKELETON. 47 sphenoid forms the septum between the orbits. The front- als form the roof of the orbits ; the alisphenoids separate the orbits from the cranial cavity ; the long slendar malar forms the very defective floor of the orbit ; the descending process of the lachrymal partially separates the orbital space from the antorbital vacuity, and the body of the lachrymal forms the antorbital process. The inferior aspect of the head is occupied posteriorly by the basisphenoid, which forms the floor of the cranial cavity. The tympanic bone lies just in front of the depres- sion for the ear. It articulates vi^ith the inferior edge of the temporal immediately vmder the base of the zyogmatic pro- cess, and extends forwards and downwards. It sends a pro- cess, the orbital process, up into the orbit, and to its distal end are articulated the malar and the inferior maxillary. The pterygoids articulate with the tympanies, under the or- bital process, then extend forwards and inwards to unite with the orbitosphenoid and the posterior extremity of the palatine. The malars are the long, slender bones, which extend from the mandibular extremity of the tympanic for- wards, to the superior maxilliary. The palatines lie inside the malars, and have the same general direction. The vom- er is a small single bone which lies between the two palatines. Posteriorly it comes oft' from the anterior border of the obit- osphenoid, and anteriorly, it terminates against the palatal plate. The mandibular branches of the premaxillar}- form the principal part of the inferior border of the opening of the nares ; while the body of the premaxillary, or the com- bined bodies of the two premaxillaries, forms the beak. The bones of the head are generally so closely united, that their limits cannot be easilv determined. For this 48 OSTEOLOGY. rensou, the skull of a very young bird, or of the embryo, should be examined with reference to the shape and limits of each bone. The descriptions which are given here, were made from three skulls of young chickens. Two of these belong to the vcvv valuable Sager collection in the Museum of the University of Michigan. OCCIPITAL BONE. This bone represents the first cranial vertebra. It en- closes the foramen magnum, and furnishes the occipital con- dyle, by means of which the head is articulated to the neck. The occipital consists of four bones, which are separate in the young, but are generally closely united in the adult skull. These bones are the basioccipital, two exoccipitals, and the supraoccipital. The basioccipital is a small triangular bone. It lies be- neath the foramen magnum, and furnishes the greater part of the occipital condyle. Inferiorly it rests upon the basi- sphcnoid, laterally it is united with the exoccipitals, and su- periorlv it terminates in the middle part of the occipital condyle. Its outer surface is raised along the base, and slants upwards, forming a depressidli, fossa subcondyloidea, just under the condyle. Its inferior border has a concavity, which is matched by a corresponding convexity in the bor- der of the basisphenoid. The condyle is semilunar in shape, and is marked by a median notch which slants to- wards the foramen. The exoccipitals form the lateral margins of the foramen magnum. They are of very irregular shape. The upper THE SKELETON. 49 part of the external surface is elevated and furnishes a pro- jection which slants downwards and outwards. .The lower portion of the external surface slants towards the basioccip- ital, and is pierced by four foramina. Through two of these foramina, pass the hypoglossus and parvagum, and accesso- rius ; through the other two, blood vessels pass. The supraoccipital forms an arch which extends from the exoccipital on one side to the corresponding bone on the other. It forms the upper margin of the foramen magnum and completes the ring. Anteriorly it unites with the par- ietal, and temporal bones. Its outer surface is strongly con- vex from side to side ; its inner surface being deeply con- cave in the same direction. It covers the cerebellum. In the skull of the owl the occipital bone is not so thick and strong as the saine bone in the chicken, nor as the parietals and frontals in the owl. The median ridge of the supraoc- cipital, directly over the foramen magnum, varies much in size and form in different species of birds. In the skulls of the hawk and owl, this ridge is short and large ; while in the skull of the goose it is long and forms a sharper ridge. The position of the supraoccipital is more nearly perpen- dicular in the skull. of the goose, than in the skull of either the hawk or the owl. On each side of the base of this ridge in the skull of the goose, there is a large foramen, which is very small or wholly absent in the skull of the chicken. In the skull of the hawk the exoccipitals are full and prominent, and the fossa subcondyloidea is deejs ; while the condyle is not notched. The occipital condyle in the skidl of the goose projects prominently, is not notched, and its superior surface is slightly concave from side to side. 50 OSTEOLOGY. PARIETAL BONES. These bones are never very large. They are united writh the supraoccipital posteriorly and with the frontals anteri- orly. Each rests upon the temporal, arches over and meets its fellow from the other side of the head. Each bone is of an irregular quadrilateral shape, presenting two surfaces and four borders. The external surface is smooth and con- vex ; the internal is irregular. At the posterior, supe- rior angle, the internal surface slants upwards and back- wards, assisting the supraoccipital in the formation of the concavity for the cerebellum. Along the anterior border , the internal surface slants forward, assisting the frontals in the formation of the concavity for the cerebrum. The su- perior border, the shortest of the three, is dentated to imite with its fellow, forming the sagittal suture. The anterior border unites with the frontal, forming the suture known in human anatomy as the coronal suture. The inferior border is thick, beveled at the expense of the outer surface, and unites with the temporal. The posterior border unites with the supraoccipital. In most adult skulls, the parietals are so closely united with the adjoining bones, that its shape and limits cannot be seen. Generally a slight transverse depression is visible along and just anterior to the coronal suture. The direction and approximate position of the line of union with the supraoccipital may be known bv the fact that it lies along and just in front of the prominent ridge which passes down each side of the supraoccipital. A small inter-parietal bone will, in some rare instances, be found. It lies at the posterior, superior angle of each parie- tal, and between those bones and the supraoccipital. THE SKELETON. 5 1 TEMPORAL BONES. The temporal bones lie, one on each side, at the base of of the parietal and just above the depression for the ear. In the adult skull, the length is about two and one-half times the breadth. It presents two surfaces and three bor- ders. The external surface is smooth and has a slight de- pression along the direction of the length of the skull. The internal surface is rough, uneven, and forms a part of the wall of the cranial cavity. The superior edge is bor- dered by the parietal and the frontal. This edge is nearly straight along the line of union with the parietal ; but from the coronal suture it becomes thin and passes- forward and downward to the inferior edge. The inferior edge is thick and rough. Posteriorly it forms a part of the upper border of the depression foi- the ear. Anteriorly it unites with the alisphenoid. Along the inferior edg?, and over the depres- sion for the ear, there is a small deep facet for articulation witn the tympanic, which forms a movable articulation at this place. Just anterior to this facet, there is a projection upon the inner surfaces of which the short process of the the alisphenoid fits. Still more anteriorly there is a second eminence bearing a groove, which passes inwards and backwards. This groove fits upon the base of the large process of the alisphenoid. In the skull of the owl, the temporal bone projects forwards and upwards, forming a thin, wide process, which stands out prominently over the temporal extremity of the tympanic bone. The process, which is given off from the inferior edge of the temporal, just over the facet for the tympanic, is the zyg- omatic process. It projects forwards and downwards and 52 OSTEOLOGY. most generally unites with the distal extremity of the post- orbital process, which is given oH' from the alisphenoid. The z3-gomatic process is the first lateral pi'ocess from the skull, from behind for^^•aIds. It is usually quite thin and sends on a projection bevond its point of union with the post-orbital process. This projection is flexible and termi- nates in a point. In the skull of the owl, the projection which has already been described as standing out promi- nently over the temporal extremity of the tympanic, corres- ponds to the zygomatic process. In this case, it does not unite with the post-orbital process. ALISPHENOID. This bone lies directly in front of the depression for the ear, and its position may be at once known by the pro- cess which projects so prominently from that part of the skull. It is united below and behind with the basisphenoid, above with the temporal and frontal and before with the or- bitosphenoid. The bone is of an irregular shape and con- sists of a body and a process. The internal surface of the body is smooth and deepl}' concave. The edge of the bone in front and above the concavity, is thick, flat, and smooth. Often there is a vertical opening through the floor of the con- cavity. The external surface is uneven and convex. Along the line of union with the basisphenoid and just in front of and below the depression for the ear, there are two (some- times only one), foramina. Also along the line of union with the temporal and just posterior to the prominent pro- ce,'5S, there is a foramen. The process slopes outwards and downwards, presenting an anterior and a posterior face ; THE SKELETON. 53 and an inferior and superior edge. The superior edge is thick and slants downwards and outwards. The inferior edge is generally conc;i\c ; though all the parts of this pro- cess ■wary in direction and extent of development. In the skull of the owl, the process of the alisphenoid does not pro- ject outwards, but downwards and forwards. It is thin and about one-half an inch wide at the base, but becomes nar- ■ rower and terminates in a point. Its anterior face is con- cave both laterally and longitudinally ; while its posterior face is convex in both these directions. It forms a small part of the floor of the orbit. In the skull of the hawk, the process of the alisphenoid projects outwards, downwaixls and slightly forwards, terminating in a point over the man- dibulax extremity of the tympanic bone to which it is united by a cartilage. In the goose, this process is yery thick, strong and blunt. It projects foi'wards and slightly outwards. In the scansores, as the woodpecker, this process is very short and has the same general shape and direction as in the rasores. The body of the alisphenoid is generally very close- ly united with the contiguous bones. The process is called, from its position, the "post-orbital" process. BASISPHENOID. This is the large, irregular bone which lies at the base of the skull. The basioccipital and exoccipitals rest vjpon the posterior border of the basisphenoid. Laterally the basi- sphenoid forms the lower part of the depression, for tlje ear, and anterior to this depression, its border slopes downward and inward, supporting the alisphenoid. From the middle point of its anterior border, the basisphenoid sends forward 54 OSTEOLOGY. a process, the. Rostrum sphenoides, which supports the ver- tical orbitosphenoid and gives attachment to the pterygoids and the palatines. The inferior face of the basisphenoid is divided into halves by a ridge, which lies in an antero-poste- rior direction. Each half is smooth, strongly convex in the direction of the length of the skull, and slightly concave in the direction of the width of the skull. The external, later- al, borders of these halves form the lower border of the de- pression for the ear. Posteriorly these borders pass up- wards and backwards, forming processes, which approach and often touch the processes of the exoccipitals ; thus form- ing a notch or a foramen, which passes from behind into the depression for the ear. Anteriorly these halves are bordered by slight eminences, which pass from the anterior, inferior angle of the depression for the ear to the base of the Ros- trum Sphenoides. Directly under the base of the Rostrum Sphenoides, there is a horizontal, triangular depression, which has for its floor a prolongation of the antero-posterior ridge which has already been described as dividing the in- ferior face into halves. On each side of the base of the Ros- trum Sphenoides, there is a horizontal fissure. Near its base, the Rostrum Sphenoides bears, on each side, an articu- lar surface which looks downwards aud outwards, and serves for the articulation with the pterygoids. The upper or internal surface of the basisphenoid is irregular. Poste- riorly it slants backwards ; anteriorly and at the base of the Rostrum Sphenoides, there is a. deep circular depression. This, like the other bones of the skull, is so closely united to the adjoining bones in the adult skull, that it can be studied satisfactorily only in the young bird. In the skull of the hawk, the inferior foce of the basisphe- THE SKELETON. 55 noid is divided into halves by a median, antero-posterior ridge, as in the chicken ; but in the skull of the owl, this sur- face is divided into halves by a depression, instead of a ridge and the two halves instead of being depressed are elevated. Indeed, in the skulls of some varieties of the domestic fowl, the inferior surface of the basisphenoid is not divided into halves by a median ridge. In the goose, the median ridge is short ; but generally very prominent. In the owl, the lateral processes from the posterior part of the inferior face, unite with the processes from the exoccipitals and form a foramen which passes from below up into the depression for the ear. In the owl, this union is so complete as to leave but a very small, or no foramen. TYMPANIC. The tympanic unites the lower jaw with the skull. It pre- sents a temporal and a mandibular extremity and an inter- mediate body, from which the orbital process is given oft'. The temporal end terminates in a small, smooth, sessile head, which fits into a depression in the inferior border of the tem- poral bone at the anterior, superior angle of the depression for the ear. The external face and posterior border are smooth and concave ; the anterior border is convex. From near the middle point of the anterior border, the orbital pro- cess extends, first upwards and inwards ; then inwards and slightly backwards. The pterygoid articulates witli the tympanic directly under the base of tlie orbital process. The body is much larger below than above the orbital pro- cess. The mandibular end presents two articular surfaces separated by a shallow depression. The external articular 56 OSTEOLOGY. surfaie, the larger of the two, is convex and projects out- wards and backwards. The malar joins the tympanic upon the outer side of the projection. There is a great difference of opinion among comparative anatomists as to the name, which should be given this bone. It has been deseribed as the homologue of the ramus ascendens of the inferior maxil-. arj- ; as the os sqamosum ; as the styloid process ; and Hux- le}-, Selenka, Parker and . others consider it as the homo- logue of the quadrate bone in fishes, or of the incus in mam- malia, and consequenth' they name it '• os quadratum." It has also been called " os pedicellatum," and has been des- cribed under this name by Coues, in his admirable memoir on the Osteology of the Colj'mbus Torquatus. It has been described as the •' tympanic" i:))- Cuvier, Meckel, Wagner, Owen, and man\- others, who regard it as tlie homologue of the t3'mpanic in the human skull. In the skull of the hawk, the tympanic is quite large and strong, and the orbital pro- cess i.s triangular, and wide and thin at and near the base. Also the depression at the mandibular extremity for the re- ception of the inferior maxillary, is large and deep. In the ovvl, this bone, like many others in the same skull, is of a cancellous structure, and not so dense as in man}- other birds. PALATINE. The palatines are two small, long bones, which are articu- lated posteriorly with the orbito-sphenoid and the pterygoids, and anteriorly with the maxillaries. Where thejr unite with the orbitosphenoid, they are expanded and thin. The two palatines do not touch each other along any part of their THK S-K.EI,ET0N. 57 course. At the posterior extremity, they are separated by the orbitospheiioid ; just anterior to this, tho\' diverge ; then pass on nearly parallel to join the maxillaries. Thc\- ai'e attached along the under surface of the maxillaries and can be distinguished by the ridge along that surface as far for- ward as the preinaxillar\'. Each is curved slightly out- wards and upwards. The palatines of the hawk are very broad and strong. The superior surface is smooth and slants from the orbitosphenoid outwards. The inferior sur- face has a sharp, prominent ridge along the posterior part of its inner edge. This ridge becomes less prominent as it extends forwards and soon entirelj' disappears. Anteriorly, the palatines, in the skull of both hawk and owl, is united with a porous, somewhat con\ohited bone, which corres- ponds to the turbinated bones in the human skull. The palatines of the owl are more curved than those of the hawk or the domestic fowl. The palatines of the goose are strong and appear as though they had been twisted. Their anteior halves diverge more than in the otlier skulls described. PTERYGOID. The pterygoids are short, strong bones which pass from the tympanic on each side, forwards and inwards. The out- er end of the pterygoid articulates with the tympanic under the base of the orbital process. This cxtremit}- is much ex- panded and makes a strong articulation with the tympanic. The inner end articulates with the Rostrum Sphenoides and the posterior end of the palatine. This extremity also is much expanded. It overlaps the posterior end of the pala- o 58 OSTEOL.OGY. tine. The body of the bone presents the appearance of hav- ing been twisted upon itself. The pterygoids act as braces to prevent the tympanic and its attached bones from being forced invi^ards. In some birds, there is an osseous connec- • tion between tlie pteiygoid and the anterior edge of the or- bito-sphenoid. In other birds, as in the owl, this connection is an articulation. About half or two-thirds the distance from the outer extremity of the bone to the point of its articu- lation with the obitosphenoid and palatine, a small process is given oft' from its posterior edge, and this process meets with a corresponding one from the anterior edge of the bas- isphenoid. The extremities of these processes are beveled so that one glides upon the other and a moveable articula- tion is thus secured. In the skull of the hawk, there is a ligamentous connection between the two bones at this point ; while in the chicken, there is no such connecfion, whatever. In the chicken, the tympanic extremity of the pterygoid as- sists in the formation of the depression for union with the inferior maxillary. ORBITOSPHENOID. The orbitosphenoid or ethmoid, is a thin vertical bone which forms a partial septum between the orbits. Its infe- rior edge rests upon and is united with the Rostrum Sphe- noides ; its superior edge is anchylosed with the inferior sur- faces of the frontals. The superior edge is much expanded anteriorly and fills the angle formed by the divergence of the anterior extremities of the frontals. This expansion ap- pears upon the external surface of the skull as a kite-shaped bone, widest anteriorly, then becoming narrower, and final- THE SKELETON. 59 ly disappearing at the point of divergence of the frontals. Tliis kite-shaped face is bounded posteriorly by the frontals, laterally by the frontals and the nasals, and anteriorly by the posterior extremities of the nasal branches of the pre- maxillaries. The inferior or internal surface of the ex- panded part is divided into halves by union along its medi- an line with the vertical part ; and each of these halves is divided into two unequal parts by a ridge which passes from the outer corner of the expanded part, backwards and in- wards to the base of the vertical part. The posterior edge is united with the alisphenoid and forms the anterior bqrder of the large circular interorbital foramen. This foramen blends with the foramen laceruni anterius^ which is bor- dered on each side by the edges of the alisphenoids and through which orbital portions of the fifth nerve pass. The anterior border is slightly concave, extends forwards and up- wards, and is beveled on each side so as to form a thin, sharp ridge. The sides of the orbitosphenoid are smooth and raised around the borders. This bone is described un- der the name of presphenoid by some authors. About half way up the anterior border of the orbitosphen- oid, a small, thin projection stands out on each side. In the skulls of the hawk and owl, these lateral projections from the anterior border are large, and project forwards and downwards. There is a groove more or less marked, along the superior border of the orbitosphenoid. This groove sei-ves for the passage of the olfactory nerve, which passes out from the cranial cavity at the posterior, superior angle of the orbitosphenoid. In the skull of the hawk, this groove pierces the base of the external lateral wings, which have been described as given oft" from the anterior border of the 6o OSTEOLCKiY. orbitosphenoid. This bone is thin, but compact, and has not the spongy structure possessed by the ethmoid of the human skull. FRONTALS. These bones form the prominence of tlie foreliead and the roof of the orbits. The sutiu'e between the two front- als is on a line with and is a continuation, in- an anterior di- rection, of the suture between the two pariefals. This line of union between the two frontals is, in some skulls, marked along its entire extent, b)- a sHght depression ; in others, all traces of a suture are obliterated ; while in a third class of skulls, there is a rough ridge along the line of union. The anterior extremity of each frontal slants outward and termi- nates in a point ; or, considering the two bones as one, the anterior extremity is deeply notched. This notch is filled by the expansion of the superior edge ofj the orbitosphenoid. The two lateral projections of the anterior extremity, are united with the nasal. The fronto-niaxillarv articulation does not allow so much movement as in the goose and many other birds. The lateral margin of the frontal is deeply con- cave forming the superior margin of the orbit. The po$terior bolder lies across the roof of the cranium, and is anchylosed with the parietals. The frontal is imited for a short distance at its external, posterior angle with the temporal. The ex- ternal surface of the frontals is subject to considerable varia- tion. Anteriorly, it is generall}- concave from side to side, or the surface of each frontal slants towards the other. The margin of the orbit is raised, forming the superciliary ridge. Just above the ridge, and separating it from the frontal emi- THE SKELETON. 6r neiice, is a semilunar depression, which is parallel with the concavity of the superior margin of the orbit. Along the bottom of this depression are numerous foramina. In some skulls, this depression is entirely wanting. Posteriorly, the external surface is more or less elevated, forming the frontal eminence. Posteriorly, the internal surface assists* in forming the roof and walls of the cranial ca\ ity ; while a plate of bone projecting from the orbital margin, hor- izontally inwards, assists in forming the floor of the same cavity. The inferior surface of this horizontal plate forms the roof of the orbit, and its posterior border unites with the alisphenoid. In the skull of the owl, the frontal emi- nence is large and prominent ; while the arch from before backwards, is high. In the skull of the goose, the frontal eminence is not prominent, and the superciliary ridges are not well defined. NASAL. The nasal is united above, with the anterior extremity of the frontal and the posterior part of the nasal branch of the premaxillary ; and below with the superior maxillary. It overlaps the long, pointed, anterior extremity of the frontal. Then extending forwards, divides into two processes. The upper and smaller one of these processes extends along, and is closely united with, the external edge of the nasal branch of the premaxillary, for about one-half the distance down the superior border of the aperture for the external nares. Here it terminates in a point. The other process passes forwards' and downwards, and anchyloses with the superior maxillary, where that bone unites with the malar. 62 OSTEOLOGY. This process forms the posterior border of the osseous bound- ary of the large aperture for the external nares, separating that aperture from the antorbital vacuity ; and it also forms the lateral osseous boundary of the nasal passages. The two nasal bones are not united in any part. At the upper extremity they are separated by the nasal branches of the premaxillary. The widest point of the nasal is near the point, where it separates into the two proceses. Here the external surface is concave from side to side, and inclines forwards and downwards. This bone is very strong and thick in the goose, where the articulation with the frontal allows considerable freedom of motion. In the skull of the hawk, the antorbital vacuity is triangular in shape, and bounded anteriorly by the descending ramus of the nasal, which separates the vacuity from the external aperture for the nares. Posterioi'ly, the antorbital vacuity is bounded by the descending process of the lachrymal bone, which separates the vacuity from the orbit. In the skull of the owl, the antorbital vacuity is almost entirely filled with the cancellated convolutions of the turbinated bone, in the same skull, the descending branch of the nasal is wide, thin and extends further forward than in the skull of the chicken. In some skulls, the descending branch of the nasal becomes very small and slender as it approaches the point of union with the superior maxilliary. The descending branch of the nasal is called by some authors the processus fnaxilla- ris ; while the branch which extends forwards is called the processus frontalis. The nasal is united with the frontal, orbitosphenoid, maxillary, preitjaxillary, and lachrymal. The union with the frontal, orbitosphenoid and lachrymal may be a movable articulation, as in the goose. THE SKELETON. 63 PREMAXILLARY. This bone is one of the largest and most important of the bones of the face. It terminates the head anteriorly and forms the osseous portion of the bill. Distallv it terminates in a point, which projects forwards and downwards. From the distal extremity back to the opening of the nares, the bone is single, and its upper surface is strongly convex, while its inferior surface is concave, forming the anterior part of the palate. Then the bone separates into three processes, a medial, nasal process, and two maxillary or mandibular processes. The nasal process really consists of two processes which lie side by side. The line of union is shown by a small median groove. This pi'ocess, or these processes, extend backwards and upwards, forming the su- perior border of the osseous boundary for the nares. Pos- teriorly the nasal branches of the premaxillary are anchy- losed with the nasals, and united with the expanded part, of the superior edge of the orbitosphenoid. The maxillary or mandibular processes diverge, pass backwards, and an- chylose with the superior maxillarv. These processes form the inferior border of the aperture for the nares. This ap- erture is of an oval shape, being larger posteriori}- than an- teriorly. The divergence of the mandibular processes, forms a narrow longitudinal opening about one-eighth of an inch broad. This opening is covered by the lining of the pal- ate. The premaxillarv is subject to great \ariation in dif- ferent species of birds. In the goose it is very large, strong and wide. The median groove along the nasal process shows that the premaxillary really consists of two bones. In the goose the part of the premaxillary anterior to the 64 OSTEOLOGY. opening for the nares, is hroad and strongly convex on its superior aspect. It is from one-half to three-fourths of an inch from the distal extremity back to the opening for the nares. The space between the two mandibnlar processes is entirely filled with the palatal plate, which is formed by lateral projections from these processes. The palatal plate is deeply concave from side to side. It bears a longitudinal median groove, which is large and deep. On each side of this median groove, there are quite a number of small grooves, which branch as thev pass forward. The premax- illary in birds of prey is generally protected by a thick, hard covering, which projects down in front and laterally below the border of the bone. Coues in describing this bone, which he calls the inter- maxillary, says : " This is by far the most important, as it is the largest and most conspicuous bone of the face ,■ its vai-ioLis modifications in the different families and orders of birds affording much the same data for zoological classifica- tion as do the teeth of mammalia." The shape .of the pre- maxillary corresponds, of course, with the shape of the beak ; or, more correcth', the form of the bone determines the shape of the beak. Con.sequently in the skulls of the hawk and owl, the distal end of the bone is hooked or curved. In the goose the nasal bones, and the nasal branch- es of the premaxillars , form a movable articulation with the anterior extremity of the frontal. By this means the upper jaw can be moved freely, at will. In the goose the opening for the nares is about three- fourths of an inch long. It is broadest at the middle point and grows smaller towards each extremity. The vomer forms a partial septum betw een the two sides. In the skull THE SKELETON. 65 of the hawk, the. opening is sliort and is widest at its anter- ior extremity. There is a complete septum between the two sides. In the owl, the opening is not as deep as in the goose and hawk. It is broadest near the middle, and there is a complete septum between the two sides, as in the hawk. In birds with short beaks, the nasal branches of the premax- ilUuy are generally. more prottjinently arched thanin those with long beaks. In the hawk there is a deep semi-circu- lar depression where the posterior extremities of the nasal branches u'nite with the frontals. MALARS. The malars are the long, slender bones which form the lateral boundaries of the inferior aspect of the skull. They are about one and a quarter inches in length, and extend from the superior maxillary back to the outer edge of the mandibular extremity of the tympanic. The anterior ex- tremity of the malar is united with both the superior max- illary and the nasal, at the point where the lower process of the nasal joins the maxillary. From its anterior extrem- ity, the bone passes backward and outwards to the tympan- ic. The malar proper extends only about three fourths this distance. Here it unites with a similar, but shorter bone •from the tympanic. These bones soon become united in the young skull ; but the point of fusion can always be de- tected even in old skulls by a rough place, due to. the blend- ing of the bones. In some instances the malar unites with the descending branch of the nasal above the point of union of the nasal with the maxillary. In this case the 66 OSTEOLOGY. malar has no connection whatever with the maxillary. The office of the malar is to transmit the motions of the tympan- ic bone to the maxillarj'. In the skull of the hawk the posterior extremity of the malar is attached to the postor- bital process by a strong ligament which is about one-fourth of an inch long. In the same skull, a wide process extends from the anterior extremity- of the malar inwards, and is fused with the turbinated bone. Also tthe anterior extrem- ity of the malar in the skull of the owl, is united with the turbinated bone. But in the latter case, the union is direct and not by means of a process as in the former. SUPERIOR MAXILLARY. In the adult skull this bone is so closely united with the contiguous bones that its limits cannot be defined. Anteri- orly it insensibly blends with the posterior extremity of the mandibular process of the premaxillary. Posteriorly it unites with the malar, palatine, and inferior extremity of the nasal. Indeed the superior maxillary is only an osseous connection between these bones. From the internal edge of the maxillary, a thin, wide process extends inwards, ap- pi'oaching a corresponding process from the other side. This process corresponds to the palatal process. In birds, the maxillary is a subordinate bone, and the important part which it fills in mammals is principally taken up by the premaxillary. In the skull of the goose, the maxillaries are larger, but their limits no better defined than in the chicken. Since this bone is so completely and closely united with the contiguous bones, it can have no motion in which they do not participate. THE SKELETON. 67 LACHRYMAL. To the anterior outer corner of each frontal, and to the adjoining upper part of the posterior border of each nasal is anchylosed a small bone known as the lachrymal. This consists of a body and a process. The body projects out- wards and upwards, over the anterior part of the orbit, and from its position may be called the supraorbital part of the lachrymal bone. The body is a thin plate about one-eighth of an inch wide, or from the point of union of the frontal with the nasal outwards, and about one-fourth of an inch in length, or from the orbit forwards. Its superior face togeth- er with the contiguous surface of the nasal and frontal is convex ; while its internal face, together with that of the nassal and frontal is concave. From the anterior part of the internal face of the body, a process extends first downwards and inwards, towards the corresponding palatine, and then downwards and outwards, approaching but not uniting with the malar. This process divides the orbital from the antor- bital vacuity. It also assists the descending ramus of the nasal in forming the very defective osseous lateral bounda- ry of the nasal passages. In the skull of the hawk the body of the lachrymal bone is quite large, extending outwards and upwards, over the orbit and articulating with a " simi- lar supraorbital derm-bone ; " while the process from the an- terior part of the under face of the body is large, strong, extends down to, and unites with the malar. In the skull of the short-eared ov^'l, {Brackyottis Cassi- inii). the process of the lachrymal bone, is verj- large, can- cellous, and unites with the malar, leaving but a very small antorbital vacuity. In the skull of the red-bellied wood- 68 OSTEOLOGY. pecker, {Ceniurus Caroliniis)., the process is wide, unites with the malar and forms a triangular antorbital vacuity. In the skull of the adult woodpecker, the body of the lach- rymal is so firmly or completely united with the frontal, that its limits cannot be defined. The union of the lachrymal with the frontal and nasal in the skull of the chicken is not very close, and consequently the lachrymal is often lost in masceration, unless due care be taken. THE VOMER. The vomer is a small single bone, which extends forwards from the anterior inferior angle of the orbitospheiioid. It lies between the two palatines, and is connected with those bones, at the point where all three unite with the orbito- .sphenoid. Its anterior extremity lies free between the man- dibular branches of the premaxillary. The vomer in the skull of the goose is thin and wide, but not strong. In the skull of the hawk the vomer is quite strong, and its posteri- or extremity seems to be clo.sely united with the correspond- ing extremities of the two palatines, while it.s anterior ex- tremity seems to be united with a turbinated bone. This bone also is often lost in preparing the skull. INFERIOR MAXILLARY. The inferior maxillary or lower jaw bone consists of a body and two rami. ,The body forms the anterior extremi- ty of the bone, is triangular in shape, pointed anteriorly, and about one-quarter of an inch long. The inferior sur- THE SKELETON. 69 face of the' bod} is strongly convex from side to side ; while the superior surface is deeply concavein the same direction. The rami, one from each posterior corner of the bod}-, di- verge, pass at first backwards and upwards, and then back- wards. Posteriorly each ramus terminates in two processes, an inner and a posterior process. The inner process pro- jects upward and inwards towards its fellow from the other ramus. Its termination is thick and rough. The posterior process extends backwards and -upwards, then slightl}- for- wards so as to form a hook. Just anterior to the base of the anterior process and at the external side of the the base of the inner process, there is a long, lateral con- cave facet which fits upon the mandibular extremity of the tympanic. The inner process corresponds to the coronoid process, of the inferior maxillary of man ; and the poste- rior process corresponds to the articular condyle, in position at least. The depression between these two processes in the inferior maxillary of man, is called the sigmoid notch. The superior edge of each ramus is convex ; while the in- ferior edge is concave. The posterior part of the external face is somewhat rough, for muscular attachment. There is considerable variation in the extent of curvature, the size and strength of the rami of this bone in difl^erent spe- cies of birds. MYOLOGY. THE MUSCLES. THE MUSCULAR SYSTEM. Of the muscular system of birds in general, Owen says : " The muscular system of birds is remarkable for the dis- tinctness and density of the carneous fibres, their deep, I'ed color, and their marked separation from the tendons, which are of a brilliant, shining color, and have a peculiar tenden- cy to ossification. This high degree of development results from the rapid circulation of very warm blood, which is highly oxygenated in consequence of the activity and extent of the respiratory functions. The energy of the muscular contractions, in this class is in the ratio of the activity of the vital functions, but its permanent irritability is proportion- ally low, as Carus has justly observed. " The tendons are especially remarkable for the degree of ossification. In regard to this fact the words of Chaveau are here quoted : " The tendons in birds present in the inferior limbs and at the extremity of the wings an amount of ossification more or less extensive along their course. This transformaHon of the fibrous tissue of the 73 MYOLOGY. muscles is not the eti'ect of senility, for it is noticed in very young animals." ;• The tendons in losing the greater part of their elastici- t\", doubtless gain in tenacity ; and this allows them to transmit to the bony levers, the muscular cMbrts in a more integral manner.'' "It is alscj observed that the partial ossihcalic^n of the tcn-