510 MONOGRAPHS <>F NORTH AMERICAN BODENT1A. 



The generalities of form of this animal arc much the same as those of 

 its nearesi allies. In relative length, the tail nearly equals thai of P. penicil- 

 latus, Imt il is uniformly haired throughout, without indication of crest or 

 penicillation. The soles are not so extensively denuded as those of P. penicil- 

 latus, owing to encroachment of hairs from the sides: still there is a fairly 

 naked strip to the extreme heed. The tuberculatum of the palms and soles, 

 and t he proportions of ail the digits, are substantially as in that species. The 

 animal is much smaller than any other species of the genus, not much exceed- 

 ing a Qricetodipus in size. Hut the most remarkable character is found in the 

 structure of the ear: it is singular how sharply distinguished some species 

 of the genus are in this respect. In P. penicillatus, a sharp teat-like pro- 

 jection of the antitragus defines the notch posteriorly, and opposite to it, on 

 the other side of the notch, there is a similar but smaller prominence of the 

 tragus bounding the notch anteriorly; thus the external edge of the ear itself 

 is altogether excluded from the formation of the notch. Now, in P monticola, 

 the lobe of the antitragus is a broad, flat, upright flap, both relatively and 

 absolutely larger than that of P. penicillatus, but there is no corresponding 

 lobe of the tragus on the other side of the notch, the front border of the 

 notch being formed by the external edge of the ear itself. This state of the 

 parts is an approach to the condition seen in Cricetodipus, and is a perfectly 

 distinctive mark of P. monticola in its own genus. This important distinction 

 escaped the describe! - of the species; but it should be added that it is only 

 fully appreciable upon examination of fresh or alcoholic specimens, and that 

 the type of the original description had been mounted when examined. Fur- 

 thermore, the ears of P. monticola are smaller than those of P. penicillatus, 

 and scarcely more than half the size of those of P. fasciatus. 



Another good character of the species is found in the softness and fine- 

 ness of the fur. The pelage is not so stiff and firm as in P. penicillatus even, 

 and has nothing of the "spun-glass" character seen in P. fasciatus, and still 

 more noticeable in P. hispidus. 



The> coloration of the species is mainly distinctive in the circumstance 

 that the dark color of the upper parts descends the fore leg to the wrist, 

 whereas on all the other species examined the whole fore leg is white. The 

 upper parts are an intimate mixture of tawny and blackish, much as in /'. 

 fasciatus. There is an evident but not very distinct lateral fulvous stripe. 

 The under parts, in the specimen described (No. 7251), are light yellow, but 



