Common Pigeon. 23 



spinatus muscle was inserted. Into the anterior surface of the 

 irregularly-shaped process were inserted the coracobrachialis in- 

 ferior and the conjoined tendons of the coracobrachialis superior 

 and subscapulars muscles, for which see Plate II. u, v, and I, with 

 description. Into its upper surface the posterior coracohumeral 

 ligament and also scapulohumeral ligament are inserted. A 

 nodule on the outer or radial side of the humerus towards the 

 lower fourth of its leng'th, marks the limit to which the insertion 

 of the deltoid reaches downwards, and itself gives origin to the 

 upper head of the extensor metacarpi radialis longior, which 

 upper head seems to represent the supinator radii longus of anthro- 

 potomy. The humerus is shorter than the antibrachium, and the 

 antibrachium than the hand-segment of the fore-limb. The three 

 metacarpals have fused with each other and with the os magnum 

 of the carpus into a single bone with a wide lacuna between its 

 elements, corresponding to the metacarpals of the index and middle 

 finger. Between the latter of these elements and the distal end of 

 the ulnar is wedged the ulnar carpal bone ; and between the former 

 and the distal end of the radius is wedged the radial carpal bone. 

 On the proximal arch and radial side of the compound metacarpal is 

 carried the pollex, consisting in the Pigeon of one phalanx ; on 

 the distal end and ulnar side of the same bone is carried the single 

 phalanx which, in this and all birds, makes up the whole of 

 the homologue of the middle digit. This single phalanx is in 

 close apposition with the lamellar portion of the strigil- shaped 

 first phalanx of the index digit, which is succeeded in the Pigeon 

 by one more which is somewhat similarly shaped; some birds, 

 however, possess three phalanges in this digit and two in the 

 pollex. 



The same proportion prevails between the three segments of 

 which the lower limb is made up, as prevails between the humerus 

 antibrachium and manus in the fore-limb; the great length of 

 the middle toe compensating for the great length of the tibia 

 on the one side, and the comparative shortness of the tai'so- 

 metatarsus on the other. The posterior extremity resembles the 

 anterior also in having a compound bone made out of elements 

 taken from parts liomologous with the carpus and metacarpus, 

 and supporting, like that bone, three digits. But it differs from 

 it in having no unanchylosed representatives of the carpal series, 



