618 MONOGRAPHS OF NORTfl AMERICAN RODENTIA. 



G. castanofs, 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 (is in other species of the genus, excepting G. his- 

 pidus, in which :t is extremely coarse and harsh). Averaging much larger 

 than any United States species (nearly equaling G. hispidus), with propor- 

 tionally smaller pouches and hands, and weaker claws (these parts being as 

 in G. hispidus). Tail and feet clot lied (as usual in the genus), not naked as 

 in Gr. hispidus and G.tuza. Length, 10-11 inches; tail, about .'> ; sole, per- 

 haps 1.50; hand, rather less. Mammas, three pairs, as in other species. 



Habitat. — 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 specimenf 

 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. iunariits, without reference to exact position. G. 

 tuza is said to have a ''single" furrow; but the proper implication is merely obsoleteness of the fine 

 inner second furrow usually seen. In G. mcxicanus, as in O. castanops, the furrow is truly tingle and 

 median ; in G. hispidus, single and internal; in G. tuza, apparently single and external. 



(No. 3533, Mils. Smiths. Inst., Xalapa, Mexico, Dc Oca. 



