616 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



Ilic main groove Insects whal is [efl of the face of the tooth, after subtracting 

 the portion cut off by the inner marginal groove; and (his latter is always 



distinct. In G. ///:a, the main groove divides what is left of the face of the 

 tooth, alter subtracting the portion cut off by the inner groove, into two 

 unequal portions, whereof the exterior is the smaller; and the inner groove, 

 always slight, may be faint, obscure, or perhaps sometimes obsolete. The 

 only other character of G. tuza I can appreciate is the nakedness of the tail 

 and feet — especially the former. The species corresponds with G. hispidus 

 in this respect. In the best-marked cases, the tail is perfectly naked beyond 

 the enlarged hairy base. The hind feet share this nakedness, but not to the 

 same extent ; the instep is nearly bare, but the toes are sparsely pilous with 

 short colorless bristles ; the back of the fore feet is in much the same con- 

 dition. The depilation of the members is not always complete ; younger 

 specimens, in the plumbago state of pelage, show as hairy tail and feet as 

 average samples of G. bursarius. The animal does not differ at all from G. 

 bursarius in size or shape. Under these circumstances, it might be held 

 that the present is merely a localized race of G. bursarius. 



GEOMYS CASTANOPS, (Bd.) LeC. 

 The Pecos, or Chestnut Pocket Gopher. 



Pseudostoma castanops, Baird, Stansbmy's Rep. Great Salt Lake, 181)2, 313 (uear Bent's Fort, N. Mex.). — 



Aid. A- Bach., Q. N. A. iii, 1854, 304. 

 Geonujs castanops, LeC, Proe. Acad. Nat. Sci. Pbila. 18:52, 163.— Baird, M. N. A. 1857, 381.— Baird, P. R. 



R. Rep. x, 1859, Gunnison and Beckwith's Route, Manim. 8, pi. 10, f. 2. — Coues, Proc. Pbila. 



Acad. 1875, 133 ; Powell's Rep. Colorado R. 1875, 233 (monograpbic). — Coues & Yarrow, 



Wheeler's Rep. Expl. W. lOOtb Merid. v, " 1875" (= 187C), 111. 

 Geomys clarkii, Baird, Proc. Acad. Nat. Sci. Pbila. 1855, 332 (Texas).— Baird, M. N. A. 1857, 383, pi. 50, 



f. 1 a-g— Kennkri.y, P. R. R. Rep. x, 1859, Whipple's Routo, Mamra. 13.— Baird, U. S. 



Mex. Bound Survey, ii, pt. ii, 1859, Manim. 41.— Gerr., Gat. Bones Br. Mus. 1862, 222. 

 Chestnut-faced and Pecos Gopher, Baird, U. cc. 



Diagnosis. — Superior incisors with a single median groove bisecting the 

 face exactly. Fore feet shorter, or not longer, than hind feet. Feet and tail 

 sparsely pilous. Color pale yellowish-brown above, inclining more or less to 

 dull chestnut about the head ; whitish below r . Size of G. bursarius, or rather 

 less. Fur soft, as usual in the genus. 



Habitat. — Texas and New Mexico. (The few specimens known to 

 naturalists are all from this limited area.) 



(Described from Baird's types of G. castanops and G. "clarkii'', and other 

 specimens.) Distinguished by the combination of a single median groove of 

 the incisors, pale lighl color, and small size. In the first-named particular, 



