260 0. C. Marsh — Descrijition of Tertiary Artiodactyles. 



" The Artiodactyles, or even-toed Ungulates, are the most 

 abundant of the larger mammals now living ; and the group 

 dates back at least to the lowest Eocene. Of the two well 

 marked divisions of this order, the Bunodonts and the Seleno- 

 donts, as happily defined by Kowalevsky, the former is the 

 older type, which must have separated from the Perissodactyle 

 line after the latter had become differentiated from the primi- 

 tive Ungulate. In the Coryphodon beds of New Mexico, 

 occurs the oldest Artiodactyle yet found, but it is at present 

 known only from fragmentary specimens. These remains are 

 clearly Suilline in character, and belong to the genus Eohyus. 

 In the beds above, and possibly even in the same horizon, the 

 genus Helohyus is not uncommon, and several species are 

 known. " 



The type specimen of the genus Eohyus is represented 

 below, natural size, in figure 1. Various other remains have 

 been found, which might be referred to this species, but they 

 give but little definite information as to its affinities, since it is 

 not certain that the reference is correct. The type specimen 

 is a last upper molar, and the characters of its crown are well 

 shown in the figure. Another upper molar shows the same 

 essential features. Judging from these specimens alone, the 

 animal would appear to have been a suilline, or at all events, a 

 bunodont Artiodactyle. Future discoveries must determine 

 its exact position. With the specimens described next below, 

 the present remains represent a distinct family, which may be 

 called the Eohyidce. 



Eohyus robustus, sp. nov. 



A larger species, which ma} T be referred provisionally to the 

 genus Eohyus, is represented by portions of a pair of lower 

 jaws with imperfect teeth, and fragments of other specimens. 

 The teeth are tubercular, and agree sufficiently well with the 

 type of the genus to be regarded as belonging to an allied 

 species. The lower jaws are very short and robust, with a 

 strong symphysis. There were apparently four lower pre- 

 molars and three molars, forming a continuous series, measuring 

 about three inches in length. The depth of the jaw below 

 the first true molar was one inch. The remains representing 

 this species are from the lower Eocene of New Mexico. 



Various remains of animals with a dentition resembling that 

 of suillines have been described by Cope under the generic 

 name Eeriptychits, which is preoccupied. These remains are 

 from the so-called Puerco deposits, or lower "Wahsatch of New 

 Mexico, a horizon lower than that in which the type of Eohyus 

 was discovered. 



