PALiEOSYOPS. 699 



modern representatives of this class of Perissodactyles the points of con- 

 trast are the wide, stout zygomas, the deep temporal fossae, the protruding 

 nasals, and the narrow gaps in the dental series of the older type. 



"There are also strong points of resemblance in the structure of the 

 Palceosyops and the Palseothere. * * * The pelvis and particularly the 

 ilium and acetabulum of Palceosyops are more palseotheroid than tapiroid. 

 The similarity in the fore-shoulder in the two types is striking. * * * 

 In the descending series of Palseotheres, terminating in the diminutive P. 

 minus and characteristic of the upper Eocene of France, we have an inter- 

 esting counterpart in the large [genus] of Palceosyops, of equal diversity of 

 size." 



I have obtained jaws and other parts of four different species of this 

 genus, which may be distinguished as follows: 



* Superior i>remolars with complete internal basal cingula. 



Length of superior molar series M. .220; external cusps of superior premolars little 

 separated ; enamel smooth P. vallidens. 



* * Internal cingula of premolars incomplete or wanting. 



Length of superior molars M. .175; external cusps of premolars well separated; en- 

 amel wrinkled P. major. 



Length of superior molars M. .150; cusps of j)remolars separated; enamel smooth. 



P. Icevidens. 



Length of superior molar series M. .100; cusps of premolars separated; enamel more 

 or less wrinkled P. borealis. 



The genus ranges from the lower to the upper Eocene. It has not 

 been found in the typical Wasatch beds of Wyoming and New Mexico, 

 but the P. borealis comes from the overlying horizon, the Wind River. The 

 P. major belongs to the Bridger, and the P. Icevidens to the Bridger and 

 allied Washakie. The P. vallidens has as yet only been found in the Wash- 

 akie. Two other species have been proposed by Leidy on specimens from 

 the Bridger, both of small size. These are the P. humilis and P. junior. 



PAL.E0SY0PS VALLIDENS Cope. 



Palseontological Bulletin, No. 7, p. 1 (August 22, 1872). Proceeds. Amer. Philo. Soc, 1872, p. 48". 

 Annual Report U. S. Geol. Survey Terrs., F. V. Haytlen, 1872 (1873), p. 591. 



Plates LI, fig. 1; LII, fig. 3; LIU, fig. 1. 



Represented by the dentition of one maxillary bone with other bones 

 of one individual; a portion of the same dentition of a second; with both 



