498 ZOOLOGY. 



skeleton coincide in their condition in any one type of ambulatory 

 mammalia, and so may well be considered together. This fact suggests 

 strongly that they are all due to a common cause." 



Of the prominences in question, it is added that " they are all imper- 

 fect in the rodentia and carnivora (except the leporidfe), which are es- 

 pecially characterized by their great speed. Among ungulates they 

 are very imperfect in the proboscidea. The orders mentioned all have 

 elastic pads on the under side of their feet or toes. The same is true 

 of the lowest types of both the artiodactyla and perissodactyla, the 

 hippopotami and rhinoceroses. In the ruminantia the trochlese are well 

 developed, with one exception, and that is the distal metacarpal and 

 metatarsal keels of the camelidiie. These animals confirm the proba- 

 bility of the keels being the effect of long-continued shocks, for they 

 are the only ruminants which have elastic pads on the inferior sides of 

 :vlieir digits." 



A New type of ungulates. 



. Through the investigations of Professor Cope there has been discov- 

 ered, in the Wasatch Eocene of Wyoming, a new type of mammal, which, 

 while related to the ordinary perissodactyles, or odd-toed ungulates, pre- 

 sents certain peculiarities which necessitate its differentiation from the" 

 existing type. The newly discovered type approaches the proboscis 

 deans, and differs from the perissodactyls in the fact that the astragalus 

 articulates with the navicular only, and by a universal convex surface, 

 as in the carnivores. 



The new type realizes the prediction long before ventured as to the de- 

 velopment of five good-sized toes on all the feet. " The cast of the brain 

 case shows that the cerebral hemispheres were quite small and nearly 

 smooth, and that the very large cerebellum and olfactory lobes were 

 entirely uncovered by them. The bones of the two carpal rows alter- 

 nate with each other, and there is a large third trochanter of the femur." 

 The animal is supposed to have been partially plantigrade It was at first 

 regarded by Professor Cope as a suborder of perissodactyla, and named 

 Condylarthra, and diagnosed by the " astragalus convex in all directions 

 distally, only uniting with navicular bone, a third trochanter of femur." 

 Recently, however, it has been elevated to ordinal distinction. 



In addition to the typical genus, named Fhenacodus, a number of 

 forms coeval with it have also since been associated with it as mem- 

 bers of the same group. 



