9 



294 PROCEEDINGS OF THE ACADEMY OF 



responding 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 con- 

 dition seen in Cricetodipus, and is a perfectly distinctive mark of 

 P. monticola in its own genus. This important distinction escaped 

 the describer of the species ; but it should be added that it is only 

 fully appreciable upon examination of fresh or alcoholic speci- 

 mens, and that the type of the original description had been 

 mounted when examined. Furthermore, 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 fineness of the fur. The pelage not so stiff and firm as in 

 P. penicillatus even, and has nothing of the " spun glass" char- 

 acter seen in P. fasciatus and still more so in P. hispidus. 



The coloration of the species is inanity distinctive in the circum- 

 stance 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 P. 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 

 this is undoubtedly the effect of alcoholic discoloration, the parts 

 being no doubt white in life. The tail is bicolor to correspond with 

 the body colors. 



While there is no question whatever of the distinctness of the 

 subject of the present article from any others described in this 

 paper, there are some points to be considered respecting its refer- 

 ence to P. monticola of Baird. The type of this species now 

 before me has been mounted and exposed to the light for about 

 twenty years ; it is faded and otherwise in poor state, the end 

 of the tail and much of the fur being; lost. The color is now a 

 uniform dull grayish-brown, much like the natural color of P. 

 penicillatus, instead of " mixed cinnamon and dusky," as origi- 

 nally described ; and the tail is uniformly dingy white, instead of 

 being " colored to correspond ;" the hairs below are all white in- 

 stead of " plumbeous at base ;" and no lateral stripe is now ap- 

 preciable, though an " indistinct" one was mentioned. But the 

 main peculiarity of the species as to coloration, namely, the 

 descent of the dark color down the fore leg to the wrist is still 



