472 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.47. 



with pale pinkish-cinnamon, giving a general color of "grayish- 

 brown"; no distinct dorsal color area, the upper side uniform with 

 back. Ears dark, thinly haired, the tufts at bases buffy and gray, 

 inconspicuous; tail dark brown above, grayish-white below; feet very 

 thinly haired with whitish. Underparts grayish-white, the underf ur 

 mixing wdth and darkening the general color from the white hair tips. 

 Adult in new short coat of late summer (90840, Hda. San Juan Capis- 

 trano, Zacatecas, August 20) : Darker, more blackish-brown on middle 

 back and rump; the sides sHghtly paler pinldsh-gray. 



Slcull. — As in ijalciensis, but palate with less regularly well developed 

 spine, sometimes concave as in true torridus. Posterior palatine fora- 

 mina smaller. 



Measurements. — Averages and extremes of six adults : Total length, 

 150 (146-153) millimeters; tail vertebrse, 52.8 (42-58); hmd foot, 

 21.9 (21.0-23.0); ear from notch in dry sMn, 16.0 (15.2-17.1). Skull: 

 Condylobasal length, 24.0 (23.5-24.9); zygomatic breadth, 12.8 (12.4- 

 13.2); interorbital breadth, 4.5 (4.4-4.8); breadth of braincase, 11.8 

 (11.6-12.0) ; length of nasals, 10.2 (9.8-10.7) ; length of mandible, 13.8 

 (13.5-14.1); maxillary tooth row, 3.7 (3.6-3.9). For detailed 

 measurements of specimens, see page 483. 



Type-specimen. — No. 90843, United States National Museum, Bio- 

 logical Survey collection. Skin and skull of female adult (teeth 

 moderately worn). Collected August 23, 1897, by E. W. Nelson and 

 E. A. Goldman. Original number, 11574. 



Remarlcs. — In the comparative uniformity of color throughout the 

 year, this subspecies differs greatly from the more northern forms of 

 Onychomys torridus, in which the variations from age and season are 

 so remarkable. The color resemblance of some adults to certain 

 examples of 0. t. tularensis is very striking. As shown by a small 

 series of skins from northern Durango, wliich, though somewhat inter- 

 mediate, have been placed with 0. t. torridus, this form blends directly 

 into the latter subspecies on the north. Tyi^ically, however, it most 

 resembles 0. t. ydkiensis. 



Specimens examined. ~Toid\ number, 14, from the following locali- 

 ties: 



Zacatecas: Hda. San Juan Capistrano, 5 (including the type). 



Aguas Calientes: Chicalote, 1. 



San Luis Potosi: Jesus Maria, 2; Rio Verde, 6. 



ONYCHOMYS TORRIDXJS StTRRUFTJS new subspecies. 



Type-locality.— yL\({vi\\m2iQ.^, Tamauhpas, Mexico. 



GeograpUc distribution.— East side of the Mexican table-land, in 

 extreme southeastern Coahuila, southern Nuevo Leon, and south- 

 western Tamauhpas. 



General characters.— L&rgest of the torridus group. Coloration in 

 new coat more reddish than in canus, approaching that of torridus 



