COLUMBA, 373 



compound bone so produced is called the furcula ; the 

 coracoid is very large and powerful and the scapula is long 

 and flat. The coracoid and scapula form the glenoid cavity 

 between them, and on the inner side the three bones border 

 the foramen triosseum. The coracoids rest upon the front 

 end of the enormous sternum, their ends being fastened in 

 its coracoid grooves. Projecting ventrally is the large keel 

 or carina and laterally there is a costal process, followed by 

 an indented costal ridge, to which the distal ends of the ribs 

 are attached. 



The fore-limb has a short and powerful humerus, a thick 

 ulna and a rather more slight radius, followed by a pair of 

 proximal carpal bones. These are succeeded by a single 



Fig. 266.— The Skeleton of a Bird's Wing. {Adnat.) 



Carpo-metacarpus. Carpal. Radius. Humerus. 



First 

 Digit. 



compound bone, the development of which shows it to be 

 composed of the distal carpals and three metacarpals fused 

 together. It is hence termed the carpo-metacarpus. It 

 bears a first digit with a single phalanx, a second digit 

 with two large phalanges and a third with one small one. 

 Hence the two peculiarities of the bird's forearm are the 

 fusion of distal carpals and metacarpals into one bone and 

 the loss of the two last digits. 



To the first digit is attached the ala spuria, a miniature 

 wing. To the hind-border of the second and third digits and 

 the carpo-metacarpus are attached the twelve primary quill- 

 feathers, and to the ulna are attached the twelve secondary 

 quill-feathers. 



