176 BULLETIN 169, UNITED STATES NATIONAL MUSEUM 



ten). He places the species in Neoclaenodon and bases his ideas of 

 Neoclaenodon on it, apparently overlooking the fact that this would 

 exclude its own genotype from this genus. Indeed "N." montanensis 

 resembles Claenodon ferox in several points, which are differences 

 from the Torre j on species liitherto confused with protogonioides, 

 such as the more rugose enamel, the stronger and crenulated cingula, 

 and the shelf-like, rather than conical, protocone on P"'. On this 

 basis the small Torrejon species might (but in my opinion should not) 

 be placed in a new genus, but the genus would not be Neoclaenodon. 



Thus, while there are single characters on which genera might be 

 founded, none of these seems either well marked or higlily significant, 

 nor are they combined in such a way as to support the separation ot 

 Claenodon and Neoclaenodon as proposed either by Gidley or by 

 Matthew. The upshot of using such characters would be to force 

 the erection of a genus for each well-defined species, a procedure not 

 useful and concordant with the really close resemblance of all members 

 of this group. 



The species previously recognized or proposed are as follovv^s: 



Claenodon ferox (Cope, 1883). Genotype. 



C. corrugatus (Cope, 1883). 



C. sp. innom. (Matthew, Pale. Mein.)i="C. protogonioides", pars, of authors 

 (in error). [C. procyonoides (Matthew, 1937) ; published too late to insert through- 

 out the present bulletin.] 



C. montanensis (Gidley, 1919). Genotype of Neoclaenodon. 



C. silberlingi (Gidley, 1919). 



C. latidens (Gidley, 1919). 



Of these, I consider C. corrugatus as a synonym of C. Jerox, and 

 C. silberlingi and C. latidens as of doubtful validity, one or both pos- 

 sibly being synonymous with C. montanensis. Another species, C. 

 vecordensis has been described from the present fauna. 



In comparing some of the Fort Union specunens with the Torrejon 

 material and in considering the general nature and limits of variation 

 and the validity of specific distinctions in this group, it has been 

 necessary to restudy the Torrejon specimens. These have in the 

 past been referred to tlu-ee species, following Cope, C. jerox, C. cor- 

 rugatus, and C. protogonioides. The type of C. protogonioides is from 

 the Puerco, and Matthew (Pale. Mem.) has shown that it belongs in 

 Protogonodon and that the Torrejon specimens hitherto placed there 

 do not belong to it but to an unnamed species (named in Pale. Mem.), 

 surely distinct from C. Jerox or C. corrugatus. 



C. corrugatus was distinguished from C. ferox by Cope as being 

 smaller and with the hypocone somewhat better developed. The 

 latter character is variable and, in the extremely slight degree in- 

 dicated by the types, seems to be individual. Matthew (Pale. Mem.) 

 considers C. corrugatus as of doubtful status but redefines it as smaller, 

 with less robust premolars, inner cusps less developed on P^~*, de- 



