458 LAND MAMMALS IN THE WESTERN HEMISPHERE 



small and low-crowned teeth which they carried. The neck was 

 of medium length, but the body was elongate and the tail was 

 very long and stout. The hip-bones were narrow and slender, 

 as in primitive ungulates generally. The limbs were short 

 and stout and retained many very primitive characteristics. 

 The humerus had a prominent deltoid crest and an epicondylar 

 foramen ; the fore-arm bones were separate and the ulna quite 

 unreduced, being almost as stout as the radius. The femur 

 had the third trochanter and the leg-bones were distinct, 

 though the fibula was slender. The feet, which were short, had 

 five digits each, but the third toe was enlarged, while the first 

 and fifth were shortened, as though preparing to disappear 

 and thus give rise to a three-toed perissodactyl foot. The 

 ankle-bone (astragalus) had a rounded, convex lower end, 

 fitting into the navicular, so that it might readily be taken for 

 that of a clawed mammal. 



2, ^MeniscotheriidcB 



A second family of Condylarthra was represented in the 

 lower Eocene by the genus fMeniscotherium and was in some 

 respects considerably more advanced than the fphenacodonts. 

 These were small animals, in which the molars had acquired 

 a crescentic pattern, recalling that seen in the early horses and 

 in the ftitanotheres and fchalicotheres, and other perisso- 

 dactyl families. In the upper molars the two external cusps 

 had been so extended as to form a continuous outer wall, each 

 of the cusps having a concave external face and the two unit- 

 ing in a prominent median ridge. The lower molars had two 

 crescents, one behind the other, as in several families of both 

 perissodactyls and artiodactyls. The body and tail were long, 

 the limbs relatively longer and lighter than those of fPhena- 

 codus and the five-toed feet were so like those of the modern 

 conies, or klipdasses, of Africa and Asia Minor, that by some 

 investigators the family has been referred to the same order, the 

 Hyracoidea, but the suggestion is not a probable one. It is 



