NO. 8 UPPER EOCENE ARTIODACTYLA — GAZIN 8l 



rather suggest Leptoreodon and the molars, though relatively high 

 crowned, are of a Leptoreodon-Leptotragulus type. 



The leptotragulids appear, with one exception, to be the only Eocene 

 artiodactyls to have early developed a simple and nearly complete 

 selenodont structure in the protomerous portion of the molars. The 

 protocone and metaconule of the upper molars and the protoconid and 

 hypoconid of the lower molars in the Uintan leptotragulines are simple 

 crescentic structures without important bifurcations, and free, except 

 in advanced wear, from the paramere, although the posterior crest of 

 the hypoconid joins or forms a lingually placed hypoconulid. It is 

 noteworthy that the posterior crest of the protocone and the anterior 

 crest of the metaconule are directed more toward the saddle midway 

 in the paramere rather than as Protoreodon. The exception noted 

 above is in the precocious Poebrotheriuin-\ike molars of Poebrodon. 

 Here the selenodonty is advanced but of a different character, in 

 which an early union is established between the crests of the inner and 

 outer cusps. 



Genus LEPTOTRAGULUS Scott and Osborn, 1887 



Synonym. — Parameryx Marsh, 1894. 



Type. — Leptotragulus proavus Scott and Osborn, 1887. 



Discussion. — Parameryx and Leptotragulus have been considered 

 synonymous since 1894 when Marsh furnished a description of 

 Parameryx. Later, when Wortman (1898) reviewed the characters, 

 he concluded that the form represented was a tylopod, but in citing the 

 name gave priority to Parameryx. Parameryx, like Eomeryx and 

 Oromeryx, was named by Marsh in an address published in 1877 ; 

 however, these were without adequate description and no types were 

 named at that time. They remained nomina nuda until 1894. There- 

 fore, if Parameryx and Leptotragulus are identical, Leptotragulus, 

 of course, has priority. It should be noted, however, that since the 

 molars of Leptotragulus and Leptoreodon are so much alike, and 

 the teeth belonging to the type material of Parameryx laevis con- 

 sist only of a few molars, there is perhaps a possibility, not too re- 

 mote, that the synonymy adopted here is incorrect and that Para- 

 meryx and Leptoreodon are synonymous, in which case Parameryx 

 would be the older term. The nature of the Parameryx laevis material 

 is highly unsatisfactory so that preservation of the status quo is much 

 to be desired. 



The genus Leptotragulus is distinguished from Leptoreodon princi- 

 pally on the basis of the premolars. The difference is perhaps less 

 noticeable in the upper premolars although P^ and P^ show evidence 



