RODENTIA—MURIJVAE-SIGMODON HISPIDUS. 
503 
upper surface of the hind feet, dirty grayish white. There is no marked difference in the colors 
of the tail, which is dusky above and paler beneath. 
The hairs are everywhere plumbeous at base, this color being darkest above. On the upper 
parts they are pale reddish brown at the ends, with the extreme tips brown ; the principal 
mixture of dark brown is, however, produced by long hairs of this color projecting far beyond 
the others. 
Description of a specimen in alcohol. —In general form, this animal closely resembles the 
large Arvicolae, the hair being long and coarse, and not forming a smooth, compact, glossy coat, 
as in the true mice generally. The tail is longer, and the ears larger, however, than is usually 
seen in the field mice. 
The head is rather narrow, hut the muzzle is very blunt, and hairy, even anteriorly ; the 
septum and region immediately around the nostrils alone being naked. The nostrils are 
termino-lateral; the septum with a groove, which is continued into the acute emargination of 
the upper lip. 
The ears may he called very large, hut are much covered by the long adjacent hairs of the 
head; they are quite orbicular, as broad as high, the convexity and posterior half of the concavity 
coated with quite long coarse hairs which lie flat, but do not form a glossy, smooth coat. The 
antitragus is well developed, elongated and quite valvular in character, capable of closing the 
meatus completely. 
The feet are quite large; the thumb of the fore foot is rudimentary, but provided with a long, 
flat nail, which completely covers it. The third and fourth fingers are longest; the second claw 
reaches to the base of the third; the fifth to the base of the second; on the hind foot, the central 
three toes are longest, and nearly equal; the first and fifth much shorter, their claws reaching 
only to the bases of the adjacent toes. The whole under surface of the hind foot is perfectly 
smooth from the extreme heel, and not at all granular as far as the first tubercles; beyond this 
the skin is rather finely tubercular, with larger tubercles interspersed; of these, there are six, 
two at the angles of intersection of the second and third, and third and fourth toes; one each at 
the bases of the first and fifth; and another behind each of these, near the inner and outer edges, 
the latter most posterior. On the fore foot there are five tubercles : one at the junction of the 
third and fourth fingers; at the bases of the second and fifth; and two on the posterior edge of 
j the palm. These last are much largest; the others, as well as those on the hind foot, being 
quite small, and appearing as if set in the surrounding skin. The skin of the soles is blackish, 
i the tubercles darker. 
The tail is rather less than the body without the head; it is conical; thick at base, and annu- 
lated. The hairs springing between the annuli, conceal them to a great extent. (2683.) 
The tubercles on the feet of Sigmodon are much smaller than those of Neotoma; the entirely 
naked soles and black skin of the former are also conspicuously different. 
This species was described as Sigmodon hispidum by Say and Ord, and as Arvicola liortensis 
by Harlan, at nearly the same time ; the former name, however, has priority in point of actual 
publication. It is very probable that the Arvicola ferrugineus of Harlan belongs to the same 
species, though this is not quite certain. 
