240 EXPLOEATION OF THE CANONS OF THE COLOEADO. 
described in this paper. The teeth of old animals are also of immense size, 
suggesting a beaver or porcupine; the under incisors sometimes protrude 
nearly an inch, while the upper ones are exposed for over half an inch. 
The next most notable feature is the nakedness of the tail and feet. The 
tail, in extreme cases, is absolutely bare not a hair or bristle can be discerned, 
even on holding the specimen up to the light, except upon the enlarged base 
In these cases, the hind feet, from the tarso-metatarsal joint outward, are 
nearly bare, though a few bristly hairs may be observed, especially on the toes. 
The hands share the same nakedness, but in less degree ; their backs are 
sparsely clothed with bristly hairs, indeed, but not in sufficient quantity to 
conceal the skin; a slight stiff fringe of hairs overhangs the inner border. 
Specimens vary in these respects; in some, delicate bristles, scarcely visible 
except when held up to a light, are scattered over the tail, and more evident 
ones clothe the instep. But the parts are never fairly hairy, as in mexicanus, 
always presenting a peculiar skinny appearance. 
There are additional characters, aside from, size and color. The very 
short tail is less than one-fourth as long as the head and body. Owing, in 
part, to a less development of the fore claws, the hands are not as long as the 
feet. The longest third claw before me is only exserted three-fourths of an 
inch, and it is usually shorter than this. The second and fourth claws are sub- 
equal to each other. The whole hand is smaller and weaker than in the G. bur- 
sarius group, indicating less fossorial nature; and coincidently with this per-* 
haps in correspondence with it the cheek-pouches are not so highly developed. 
As well as can be judged from prepared skins, the sacs do not reach beyond the 
head certainly not to the shoulder; their capacity, in an individual nearly a 
foot long, seems no greater than that of specimens of G. bursarius eight 
inches long, and not more than half as bulky. 
The hispid pelage is a remarkable feature; this is so strong a character 
that the species may readily be diagnosticated in the dark by the "feel" of the 
fur, and it is instantly noted in comparison with any of the other species, in 
which the pelage is sleek and soft, much like a mole's. Besides being so 
coarse and harsh, and almost entirely lusterless, it is longer than usual, and 
interspersed with still longer and almost bristly hairs. There is no percept 
ible under-fur different from the general pelage ; and the color is uniform to 
