106 THE MERYCOIDODONTID/K 



which I gravely doubt, then the former species could well have given rise to Cope's species. 

 P. gregoryi loomisi is not easily allied with any other species in skull proportions, but in some of the 

 characters of the skull and in many more of the skeleton it shows a marked similarity to P. gregoryi. 

 The dental indices are nearer to those of P. carrikeri, another Wyoming species, but the bodily 

 proportions are very different between the two. Probably its true affinities lie with P. gregoryi, as a 

 female of a very large variety of the latter. 



P. macrostegus appears to be similar in many ways to P. m. grandis; P. chelydra is nearly of a 

 size with P. gregoryi but has a considerably longer muzzle and tooth row, while still others of the 

 John Day seem to have affinities with certain Great Plains forms. 



It is hoped that my present grouping will stimulate interest in the discovery of more critical 

 material to help in definitely placing the members of this very large, widespread, and important 

 division of the oreodonts. 



Etymology: Promerycochosrus (before + Merycochoerus); Paracotylops (near + Coty- 

 lops); Desmatochosrus (bond + hog); Hypselochcerus (high + hog). 



Species: 



P. carrikeri M Peterson 1906. 



P. chelydra F (Cope) 1 884. 



P. chelydra latidens M Thorpe 1921. 



P. curvidens F (Thorpe) 1921. 



P. erythroceps Stock 1932. 



P. gregoryi M-F Loomis 1 924. 



P. gregoryi loomisi F Schlaikjer 1934. 



P. hesperus Stock 1930. 



P. hollandi M Douglass 1907. 



P. hollandi hatcheri F Douglass 1907. 



P. hollandi minor M Douglass 1903. 



P. leidyi F (Bettany) 1 876. 



P. lulliF Thorpe 1921. 



P. macrostegus M (Cope) 1884. 



P. macrostegus infiatus M Thorpe 1921. 



P. marshi M Thorpe 1921. 



P. microcephalus F Thorpe 1 92 1 . 



P. montanus F (Cope) 1884. 



P. montanus grandis F Douglass 1907. 



P. superbus F (Leidy) 1870. Genotype. 



P. thomsoni M-F Loomis 1924. 



P. vantasselensis M Peterson 1906. 



P. vantasselensis pygmceus M Loomis 1924. 



Promerycochcerus carrikeri Peterson 1906 

 Figs. 68-70; PI. X, fig. 1 ; PI. XLV, fig. 1 



Original Reference: The Miocene beds of western Nebraska and eastern Wyoming and their verte- 

 brate fauna;. Ann. Carnegie Mus., IV, pp. 26-28, pi. IX. 



Type Locality: Head of Warbonnet Creek, Sioux County, Nebraska. 



Geologic Horizon: Lower Miocene (lower Harrison). 



Types: Holotype, Cat. No. 1080 CM., nearly complete skeleton. Paratypes, Cat. Nos. 1078, 1079, and 

 1081 CM., partial skeletons; Plesiotypes, Cat. Nos. 109, 1047, and 1228 CM., skull, jaws, and skeletal 

 elements. Species named in honor of M. A. Carriker, Jr. 



