618 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
G. castanoys, which is very different in size and color). Coloration and general 
appearance of G. bursarius (which has two distinct grooves on the upper 
incisors). Fur soft, sleek (as in other species of the genus, excepting G. his- 
pidus, in which it is extremely coarse and harsh). Averaging much larger 
than any United States species (nearly equaling G. hespidus), with propor- 
tionally smaller pouches and hands, and weaker claws (these parts being as 
in G. hispidus). Tail and feet clothed (as usual in the genus), not naked as 
in G. hispidus and G. tuza. Length, 10-11 inches; tail, about 3; sole, per- 
haps 1.50; hand, rather less. Mamme, three pairs, as in other species. 
Hasirar.—Mexico. (Limits of distribution unknown. Not known to 
occur north of Mexico.) 
Shares with G. castanops the single median* furrow of the upper inci- 
sors, but is much larger and different in color. The well-prepared speciment 
here described is only equalled in a large series of G. bursarius by a single 
much over-stuffed example. The pouches, as well as can be judged from the 
skin, are smaller proportionally than those of the United States species; in: 
this respect being like those of G. hispidus. These two Mexican species 
further agree in the relative smallness of the hands and less enormous devel- 
opment of the claws; the fore member being shorter or, at most, not longer 
than the hinder one. The orifice of the external ear presents, in the dried 
state, a mere rim, around which no flap can be fairly recognized. In color, 
the specimen is not decidedly different from bursarius, though there is a 
purity of the chestnut-brown which contrasts with the muddy-brown (in 
some cases almost a glaucous shade or “‘bloom”) commonly seen in bursarius. 
The fur is deep plumbeous basally, pointed with the warm brown on the 
upper parts, and only partially hidden below by muddy-gray and hoary ends 
of the hairs. Auricular region darkened. Hind feet and tail mostly whitish. 
There is some whitishness about the lower jaw, and a small white abdominal 
and anal patch; these last being of indeterminate character. The plumbago 
or “anthracite” variation of pelage occurs in this as in other species of this 
family. 
* 
* G. hispidus has been described as having a single median furrow; the emphasis here, however, is 
upon “single”, in antithesis to the double furrow of G. bursarius, without reference to exuct position. (By 
tuza is said to have a “single” furrow; but the proper implication is merely obsoleteness of the fino 
inner second furrow usually seen. In G. mexicanus, as in G. castanops, the furrow is truly single and 
median ; in G. hispidus, single and internal; in G. tuza, apyarently single and external. 
t No. 3532, Mus. Smiths. Inst., Xalapa, Mexico, De Oca. 
