SKELETON OF THE COMMON PIGEON. 6 1 



on the internal, or true anterior, border in contact with the acromion. A 

 rough line runs downwards from it to the broad sternal or epi-coracoidal 

 end of the bone and gives attachment to the coraco-clavicular membrane. 

 The coracoid fits into a groove in the sternum. The furcula, a characteristic 

 Avian bone, is formed by the fusion of the ventral ends of the two clavicles. 

 At its upper end each clavicle expands into a disc or epicleidium, which 

 is tied by ligament to the acromion and to the sub-scapular and clavicular 

 processes of the coracoid. There is thus formed a foramen triosseum 

 through which the tendon of the second pectoral muscle, or elevator of the 

 wing, passes to its insertion on the humerus. The spot where the ventral 

 ends of the clavicles fuse is prolonged into a point, the homologue of the 

 large hypocleidium in the Fowl, and united as it is to the keel of the 

 sternum by a ligament which together with the point represents a portion 

 of the interclavicle. 



The fore-limb of this specimen is in the position of rest. The humerus 

 lies parallel to the axis of the body, its true ventral surface turned outwards ; 

 the fore-arm is flexed on the humerus and the hand is adducted. When the 

 wing is expanded, the hand is abducted : it is incapable of flexion. As 

 to the humerus, its glenoid head is transversely elongated : on its radial 

 or upper margin at the proximal end is a conical process to which the 

 first pectoral, or depressor of the wing, is attached, and dorsally to it is 

 the facet for the insertion of the second pectoral. On the ulnar margin 

 proximally and dorsally is a deep pit, at the bottom of which is a pneumatic 

 foramen. The surface of articulation for the radius is longyDblique and on 

 the ventral surface, as in Lizards. The radius is rod-like ; the ulna stout, 

 somewhat curved, and with a short olecranon. Its outer surface is pitted 

 by the sacs of the secondary wing feathers. There are two carpal bones 

 in the proximal row a scaphoid (= radiale), and a fused lunar and 

 cuneiform (= intermedium and ulnare). The distal carpalia are fused to 

 the heads of the metacarpalia, forming a carpo-metacarpal bone. The first 

 metacarpal is a mere process and carries a single phalanx ; the second 

 is stout and long and carries two phalanges ; while the third is slight, 

 curved and fused distally to the second, and carries but one phalanx. In 

 no Bird are there more than these three digits. 



The pelvis has the three bones ileum, ischium, and pubis peculiarly 

 disposed. The first extends backwards and forwards along the whole 

 extent of the sacrum ; the ischium lies parallel to the backward extension 

 of the ileum ; the pubes to the ischium, and neither of the two latter have 

 a ventral symphysis. All three unite in the acetabulum. The centre of 

 this cavity is membranous in the living animal. Hence in a prepared 

 skeleton it appears to be perforated. A prominent surface the anti- 

 trochanter on the posterior-superior margin of the acetabulum, works 

 against the base of the neck which carries the head of the femur. Ileum 



