NO. 8 UPPER EOCENE ARTIODACTYLA GAZIN 47 



defined metaconid on P4. The form of P4, like that of S. hudsoni, 

 corresponds more closely to that of Hypertragulus than it does to 

 Leptomeryx. The molars of 5. uwiufus are almost identical to those 

 of 6". hudsoni. 



Family AGRIOCHOERIDAE Leidy, 1869 

 Genus PROTOREODON Scott and Osborn, 1887 



Synonyms. — Eomeryx Marsh, 1894. 

 Hy ornery X Marsh, 1894. 



Agriotherhnn Scott, 1898 (not Wagner, 1837). 

 Chorotherium Berg, 1899. 

 Protagriochoerus Scott, 1899. 

 Mesagriochocrus Peterson, 1934. 



Type. — Protoreodon parvus Scott and Osborn, 1887. 



Discussion. — Much of the taxonomic confusion earlier referred to 

 for upper Eocene artiodactyls relates to the redundance of generic 

 names that have been applied to these small agriochoerids. Marsh's 

 name Eomeryx first appeared in 1877 in the published text of an 

 address, but as it was given without adequate description and without 

 designation of species it remained a nomen nudum until 1894. In the 

 meantime, Scott and Osborn (1887) described the genus and species 

 Protoreodon parvus from the Uinta. In 1894 Marsh announced that 

 the type of his Eomeryx was the earlier-named species (1875) 

 Agriochoerus pumilus, and at the same time named as new, Hyomeryx 

 hreviceps. The generic name Agriotherium (preoccupied) was given 

 by Scott to his new species "A." paradoxicus in 1898, which Berg 

 replaced by Chorotherium. In Scott's monograph on the selenodont 

 artiodact}ds of the Eocene in 1899 he reassigned this species to 

 Protoreodon and at the same time named the relatively large Pro- 

 tagriochoerus annectens. More recently (1934) Peterson contributed 

 to the growing list of s}Tionyms by proposing Mesagriochoerus for 

 the Duchesne River protoreodont. 



From a review of all the types involved and much referred ma- 

 terial, I have been led inescapably to the conclusion that Protoreodon, 

 as Peterson (1919, p. 82) indicated, was essentially an agriochoerid 

 and not a mer\-coidodont. It is unfortunate that the name Protoreodon 

 should be the one to survive, but there appears to be no doubt of its 

 priority. 



Protoreodon differs from Agriochoerus principally in the less- 

 molarized form of P* and P4, retention of a protoconule on the upper 

 molars, absence of any appreciable diastema behind the upper canine 



