616 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
the main groove bisects what is left of the face of the tooth, after subtracting 
the portion cut off by the inner marginal groove; and this latter is always 
distinct. In G. zwza, the main groove divides what is left of the face of the 
tooth, after 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. 
Pscudostoma castanops, BAIRD, Stansbury’s Rep. Great Salt Lake, 1852, 313 (near Bent’s Fort, N. Mex.).— 
Aub. & Bacu., Q. N. A. iii, 1854, 304. 
Geomys castanops, LEC., Proc. Acad. Nat. Sci. Phila. 1852, 163.—Barrp, M. N. A. 1857, 381.—Barrp, P. R. 
R. Rep. x, 1859, Gunnison and Beckwith’s Route, Mamm. 8, pl. 10, f. 2.—Couxs, Proce. Phila. 
Acad, 1875, 133; Powell’s Rep. Colorado R. 1875, 233 (monographic).—Cours & YaRRow, 
Wheeler’s Rep. Expl. W. 100th Merid. v, “ 1875” (= 1876), 111. 
Geomys clarkii, BatrD, Proce. Acad. Nat. Sei. Phila. 1855, 332 (Texas).—Batirp, M. N. A. 1857, 383, pl. 50, 
f. 1 a-g.— KENNERLY, P. R. R. Rep. x, 1859, Whipple’s Route, Mamm. 13.—Barrp, U. S. 
Mex. Bound Survey, ii, pt. ii, 1859, Manim. 41.—Grrr., Cat. Bones Br. Mus. 1862, 222. 
Chestnut-faced and Pecos Gopher, Baird, Ul. cc. - 
Diacnosis.—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. Size of G. bursarius, or rather 
less. Fur soft, as usual in the genus. 
Hapirat.—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 light color, and small size. In the first-named particular, 
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