I 93-] Allen* Mammals front New Mexico and Duraiigo. 603 



shorter and nearly 2 mm. wider, with very much heavier 

 dentition (molars much broader), and a shorter and more 

 strap-shaped interparietal. In coloration and external 

 measurements the two forms are similar, but durangcs is less 

 fulvous. It perhaps should be compared with N. i. melanura 

 Merriam, from Ortiz, Sonora, from which, however, it appears 

 to differ in having a larger head and body and much shorter 

 tail, and by the absence (generally) of an antero-internal 

 sulcus on m 1 . No skull measurements were given of melanura, 

 but the skull is described as smaller, with narrower nasals,, 

 than albigula, which is not the case with duranga. 



1 6. Thomomys sinalose Merriam. 

 Rio Sestin, i specimen, April n. 



17. Thomomys, sp. 



^ 



Two specimens: Mt. San Gabriel, i, Jan. 28; Matalotes, i, 

 March 20. They differ widely in coloration and probably 

 represent two species, but the skull of one is too much broken 

 for use in comparison. 



1 8. Perodipus obscurus, sp. nov. 



Type, No. 20957, $ ad., Rio Sestin, northwestern Durango, April 

 13; J. H. Batty. 



General color of dorsal area gray brown slightly suffused with ful- 

 vous, resulting in a faintly olive gray brown effect; flanks more 

 strongly suffused with fulvous, which is here the prevailing color; 

 lower parts, including fore limbs, lower half of cheeks and sides of 

 neck, clear white to base of hairs; tip of nose and a narrow line running 

 back on each side of base of whiskers black; exterior surface of ears 

 buffy whitish, nearly white apically and at base, antero-external bor- 

 der and inner surface blackish; small spot above eyes, post auricular 

 patch, and oblique band on thighs white; outside of hind limbs to the 

 tarsal joint like the back, inside white, soles dusky brown; tail with 

 the sides and a basal ring white, the upper and lower surfaces blackish 

 from base to tip, the upper surface heavily crested for about the ter- 

 minal third. 



Measurements. Type, total length, 232; head and body, 102; 

 tail vertebrae, 130; hind foot, without claws, 32, with claws, 35; ear 

 from notch, 12.7. Skull with a broad rostrum, as in P. agilis, with 



