1898.] Woriman, Extinct Camclida. of North America. I 29 



Dr. Leidy again described some large Camel remains from Cali- 

 fornia, which he referred to the living genus Aicchenia} Follow- 

 ing this Cope^ described two new genera, Holomeniscus and 

 Eschatiiis, which he based upon fragmentary materials from 

 Oregon, Mexico and elsewhere. He distinguished these genera 

 from Pliauchenia, Atichenia and Cavieliis by the possession of a 

 single superior premolar, the fourth, and separated Eschatins from 

 Holomeniscus by the extreme reduction of this tooth to a simple 

 cone. The evidence upon which a knowledge of the superior 

 premolar dentition of these forms rests is furnished, so far at least 

 as I have been able to learn, by (i) a fragment of an upper jaw 

 oi H.vitikerianus, containing the first and second molars, together 

 with the roots and alveoli of the premolar or premolars immedi- 

 ately in advance, as well as a portion of the free border of the 

 jaw ; (2) a much damaged fragment of a superior maxilla of H. 

 hcsternus, in which no knowledge of the premolar dentition is 

 possible, since neither the teeth nor their alveoli are preserved ; 

 and (3) a portion of a superior maxilla of Eschatius conidens with- 

 out teeth but having nearly all the alveoli preserved. 



It ap])ears from a careful examination of this material that the 

 number of superior premolars in all these Pleistocene cameloids, 

 with the exception of Eschatius conidens.^ is uncertain. In the only 

 specimen in which it can be possibly made out, there are 

 undoubted traces of an alveolus for a third premolar. If there 

 were two premolars above, then the dental formula is the same 

 as in the living genus Auc/ienia, and is indistinguishable from it, 

 so far, at least, as the number of teeth is concerned. The 

 third superior premolar is very small in Auc/ienia, and it will 

 not be surprising to find, when a larger number of suitable 

 specimens of these North American Pleistocene species are 

 known, that in some cases a vestige of this tooth remained in 

 the jaw for a longer or shorter time during the life of the animal ; 

 at least this seems to be the rule in many cases wherein a tooth 

 is about to disappear from the series. 



I therefore reject the definition given by Cope, but retain the 

 genus as distinct from Auchenia, upon an entirely different 



1 Report U. S. Geolog. Surv. Territories, 1873, p. 225. 

 ^ Proc. Amer. Philos. Soc, 1884, p. 16. 



{April, iSgS.] 



