68 



BULLETIN 171, UNITP^D STATES NATIONAL MUSEUM 



pelage. In an examination of a series of Recent skulls and jaws in 

 the collections of the U. S. National Museum and U. S. Biological 

 Survey, it was found that they show a wide range of individual and 

 sex variations and that it was apparently not feasible to formulate a 

 series of definite characters that would satisfactorily separate the 

 two species. 



The specimens from Cumberland Cave Ukewise show considerable 

 variation but apparently not exceeding in any important details the 

 limits of individual variation seen in modern specimens. 



riQURE 37.— Erethuon cf. dorsatum (Linnaeus): a, Skull (U.S.N.M. 7996), lateral view; 6, mandible (U.S. 

 N.M. no. 7672), lateral and occlusal views. Two-thirds natural size. Cumberland Cave Pleistocene, 

 Maryland. 



A remarkably large skull (fig. 37a), U.S.N.M. no. 7996, in the cave 

 collection is characterized by a noticeably broad frontal region, wide 

 palate, and particularly broad incisors. The incisors appear to be 

 sHghtly wider than in the Recent specimens examined, although other 

 proportions characterizing tliis skull seem to be duplicated in some 

 of the larger of the modern specimens. 



Order LAGOMORPHA 

 Family OCHOTONIDAE 



OCHOTONA species 



Six fragmentary mandibles and three maxillary portions, all carry- 

 ing teeth, are recognized as belonging to a species of Ochotona. With 

 this limited material no important differences can be cited separating 



