276 MEMOIRS OF THE CARNEGIE MUSEUM 
I fully agree with Matthew in the taxonomic position of Oligobunis. Furthermore 
it is quite evident that the present genus is closely related to the John Day form 
and quite likely in a direct line of descent which the generic name used implies. 
Oligobunis lepidus Matthew (J. c., p. 194) is a connecting type; it is a smaller species 
than the John Day form, but indicates a type specialized differently from the present 
genus, having Mz very much less reduced, while P;is more reduced than the same 
tooth in the present genus, indicating greater tendency towards the loss of one tooth 
and the retention of the other in O. lepidus than in Paroligobunis simplicideus. Mz 
in O. lepidus is one half the antero-posterior diameter of the carnassial, while that 
tooth in the present genus is only one third the antero-posterior diameter of the 
carnassial, plainly showing that in the present genus there is a more strongly marked 
advance toward modern forms. 
Potamotherium (= Stephanodon) of Europe has a general resemblance to the new 
genus here proposed, but it is quite clear that this European form is at least generi- 
cally different. In comparing the present type specimens with Dr. Schlosser’s * 
figures, it is seen that Pz in the American form is smaller, the premolar series 
increases more in size, from before backward in the jaw, the metaconid of M+ is less 
developed and placed higher up on the crown, and the heel is smaller. Upon 
further comparison it is seen that the lower jaw is deeper and shorter in Paroligo- 
bunis. Of especial importance is the proportion of the hind limbs of the two genera. 
In Potamotheriwm the femur is shorter than the tibia, an aquatic feature, while 
in Paroligobunis the femur is longer than the tibia. The material at hand displays 
further comparison which may, however, be regarded as of less importance between 
these two genera; namely, the more strongly developed cingula and accessory 
tubercles of the premolars, and the external position of P; in the European form, 
while in Paroligobunis simplicidens Pz is internal due to the reverse obliquity of Pz 
in the latter. 
Paroligobunis (Potamotherium) lacota which was provisionally referred to the 
European genus by Matthew and Gidley” appears to be quite closely related to 
Paroligobinus simplicidens having apparently somewhat smaller canines and a slen- 
derer jaw than the latter species. Dr. Matthew states (J. c., p. 254) that Cope’s type of 
Potamotheriwm (Lautrictis) lycopotamicus is lost and cannot be verified with Cope’s 
reference, there being no illustrations of the type specimen. 
Stenogale (Potametheriwm) robusta Cope was based on a lower jaw containing part 
of the dentition and was found in the Upper Miocene near Fort Niobrara, Nebraska. 
28 Beitrage Paleontologie Osterich-Ungars und des Orients, Pl. VIII, figs. 18, 63, 64, 65, 1888. 
29 Bull. Amer. Mus. Nat. Hist., Vol. XX, p. 254, 1904. 
