502 THE VERTEBRATE SKELETON. 



which does not nearly reach the carpus. In the Tylopoda, 

 though the ulna is complete and its distal end is often distinct, 

 it has coalesced with the radius throughout its whole length ; 

 the olecranon is generally very large. 



SUBUNGULATA. In the large Condylarthra the humerus 

 has an ent-epicondylar foramen, and the radius and ulna are 

 stout bones nearly equal in size. 



In Procavia the humerus is rather long, and has a very 

 prominent greater tuberosity, and a large supratrochlear fossa, 

 but no ent-epicondylar foramen. 



In the Proboscidea the humerus is marked by a greatly 

 developed supinator ridge, and is very long, longer than the 

 radius and ulna. The ulna has a remarkable development, 

 having its distal end larger than that of the radius, it has 

 also a larger articular surface for the humerus than has the 

 radius. 



In RODENTIA the humerus varies much in its development 

 according to the animal's mode of life. In the Hares it is long 

 and straight, with a small distal end, and a slight deltoid ridge. 

 In the Beaver on the other hand the deltoid and supinator 

 ridges are considerably developed. There is generally a large 

 supratrochlear fossa, but no ent-epicondylar foramen. 



CARNIVORA. In the Carnivora vera the humerus has large 

 tuberosities, a prominent deltoid ridge and a deep olecranon 

 fossa. The shaft is generally curved, and an ent-epicondylar 

 foramen is often found, though not in the Canidae, Hyaenidae, 

 and Ursidae. The radius and ulna are never united. The 

 radius (fig. 77, B) has a very similar development throughout 

 its whole length, while the ulna has a large olecranon (fig. 

 77, C, 11) and a shaft tapering somewhat towards the distal 

 end. 



In the Pinniped ia the arm bones are very strongly de- 

 veloped. The humerus has a very prominent deltoid ridge, 

 and the proximal end of the ulna and distal end of the 

 radius are much expanded. 



