266 O. C. Marsh — Description of Tertiary Artiodactyles. 



Eomeryx piimilus , Marsh . 



Among the interesting fossils found by the writer in the 

 Uinta basin, in 18T0, were remains of three small Artiodactyles, 

 each with selenodont dentition, the earliest then known in. the 

 country. One of these animals was described under the name 

 Agriochmrus pumilus* as the lower teeth and other portions 

 secured resembled strongly the corresponding parts pertaining 

 to that genus, as known from a higher horizon. Subsequent 

 discoveries proved that these remains were distinct from those 

 of Agriochwrus, the upper molars resembling more nearly 

 those of Ancodus {ECyopotamus), but in reality representing a 

 new genus, which was named by the writer Eomeryx, in the 

 address already cited.f 



18. 



Figure 18. — Upper teeth of Eomeryx pumilus, Marsh; seen from below. 

 Natural size. 



In the address quoted, the writer defined the Uinta Artio- 

 dactyles with selenodont dentition, as follows : " In the 

 Diplacodon horizon of the upper Eocene, the Selenodont den- 

 tition is no longer doubtful, as it is seen in most of the 

 Artiodactyla yet found in these beds. These animals are all 

 small, and belong to at least three distinct genera. One of 

 these, Eomeryx, closely resembles Homacodon in most of its 

 skeleton, and has four toes, but its teeth show well marked 

 crescents, and a partial transition to the teeth of Hyopotamus, 

 from the Eocene of Europe. With this genus, is another 

 (Earameryx), also closely allied to Homacodon, but apparently 

 a straggler from the true line, as it has but three toes behind. 

 The most pronounced Selenodont in the upper Eocene is the 

 Oromeryx, which genus appears to be allied to the existing 

 Deer family, or Cervidce, and if so is the oldest known repre- 

 sentative of the group. These facts are important, as it has 

 been supposed, until very recently, that our Eocene contained 

 no even-hoofed mammals." Again in speaking of the Oreo- 

 donts in the Miocene, the following statement is made : " The 

 least specialized, and apparently the oldest, genus of this 

 group is Agriochmrus, which so nearly resembles the older 

 Hyopotamus, and the still more ancient Eomeryx, that we can 

 hardly doubt that they all belonged to the same ancestral line." 



*This Journal, vol. is, p. 250, March, 1875. 

 f Ibid., vol. xiv, p. 364, November, 1877. 



