THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE III. VOL. III. 



No. II.— FEBRUARY, 1886. 



OUIGHSTAL ABTICLES. 



I. — Prof. E. D. Cope, on a New Type of Perissodacttle Ungu- 

 late from the Wasatch Eocene of Wyoming Territory, 

 United States of North America. 

 (PLATE II.) 



IN his last published volume on the Yertebrata of the Territories, 1 

 Prof. Edward D. Cope has figured and described many new 

 and remarkable forms of the Order Ungulata from the Eocene of 

 Wyoming. The most important and interesting among the numerous 

 species described being the genus Phenacodus, of which the nearly 

 entire skeletons of two species have been discovered, namely P. pri- 

 mcevus, represented in our plate (Plate II.) and P. Vortmani. So 

 far as the present evidence goes, Phenacodus appears to have been the 

 most generalized form of a Perissodactyle Ungulate hitherto described, 

 though other contemporary genera may ultimately show characters 

 as generalized, when the relation of those species founded upon the 

 dentition to those founded on the detached bones of the extremities 

 is better known. The teeth of Phenacodus are tuberculated, with 

 intervening valleys, resembling the dentition of some of the bunodont 

 Artiodactyla, whilst the femur has a third trochanter, and the fore and 

 hind feet have each five well-developed digits, showing it to be a 

 Perissodactyle or odd-toed ungulate. 



Again, the scapula is widened anteriorly, as in the Ursine Carnivora, 

 the Amblypoda and Proboscidea. With the last group the form of 

 the ulna also coincides, being large and broad relatively to the radius, 

 and also in that the bones of the carpus do not interlock. 



From these coincidences of structure Prof. Cope says, "This genus 

 must be placed in a special group of an order which includes the 

 Proboscidea " (p. 383). On the other hand, in a lecture on the Horse, 

 recently delivered at the City of London Institute, Prof. W. H. 

 Flower, LL.D., F.R.S., infers, from certain structural characters, that 

 it was an early ancestor of the Equidce. However, the following 

 general description of the genus (extracted chiefly from the " Ameri- 

 can Naturalist," 2 and reproduced again in Prof. E. D. Cope's later 

 and grander work) will better serve to convey, in the author's own 



1 " Eeport United States Geological Survey of the Territories," F. V. Hayden. 

 vol. iii. " The Vertebrata of the Tertiary Formation of the West," Edward D. 

 Cope. Washington, 1884 (inner title 1883) ; 4to. pp. xxxiv. and 1009; plates 75, 

 several folding. 



2 The American Naturalist, vol. xv. 1881, p. 1017. 



DECADE III. VOL. III. — NO. II. 4 



