286 PROCEEDINGS OF THE ACADEMY OF 



foot, the sole is perfectly naked for its whole length along a median 

 strip, narrowed by encroachment on either side of a fringe of hairs. 

 On the outer side, about half-way from heel to base of digits, is a 

 small tubercle; there is another near the base of the 1st digit, 

 and a much larger one near the base of the 5th digit, with others 

 still at the bases of the intermediate digits ; but their precise dis- 

 position, and the character of the naked sole cannot be made out 

 perfectly. The first digit is very small, with a smooth bulbous 

 end and short blunt claw ; the other claws are of a more ordinary 

 character, but relatively shorter, blunter, less compressed and less 

 curved, than those of the hand; they are excavated underneath. 



The tail is completely but rather thinly haired ; and, especially 

 toward the end, the hairs stand apart and are somewhat lengthened 

 (as is usual in the genus); still they do not develop into the 

 decided comb or crest, or tuft at the end, which is characteristic 

 of P. penicillatus. 



The pelage of this species is coarse, harsh, and stiffish (as in 

 other species of typical Perognathus), though not to a degree which 

 could bear the term "spiny" or even bristly; it has been likened 

 to fine-spun glass, though such expression might be considered 

 strong, unless excessively delicate glass is meant. The fur has 

 considerable gloss ; there is no under fur whatever. The character 

 seems to me to be much as in the murine Sigmodon hispidus, and 

 in fact the specimens before me have considerable superficial resem- 

 blance to the young of that species. A likeness to Jaculus hudso- 

 nius is perhaps even stronger. The color of the upper parts is a 

 light sandy-yellowish, closely lined throughout with blackish, 

 producing a fine grizzle. The greater part of the length of the 

 individual hairs is the color of barely tarnished cut lead; rather 

 light, and unlike the heavier plumbeous of most rodents. This is 

 succeeded by the sandy ends of the hairs ; a part of them are of 

 this last color to the very end, while others have the tips blackish, 

 producing the grizzle above mentioned. The line of demarcation 

 of this color begins on the side of the nose, and runs straight over 

 the shoulder and sides of the body, descending the hind limb to 

 the heel. To this succeeds a strip of rich reddish-yellow or 

 salmon-color, beginning on the cheeks and following the line 

 already indicated to the heels, but also descending a little way on 

 the fore leg. This color is pure, the hairs being so colored to the 

 roots, there being no plumbeous basal portions and no blackened 



