RODENTIA—SCIURINAE—SPERMOPHILUS MEXICANUS. 319 
SPERMOPHILUS MEXICANUS. 
Mexican Ground Squirrel. 
Sciurus Mexicanus, ERXLEBEN, Syst. Ann. 1777, 428. 
Citillus Mexicanus, Licurenste1n, Darstel. Saugt. 1827, 1834; tab. xxxi, fig. 2, (Toluca.) 
Spermophilus Mexicanus, Wagner, Supp]. Schreb. IIT, 1843, 250. 
Aup. & Bacu. N. Am. Quad. IT, 1853, 39; pl. cix, (exclusive of fig. of supposed young.) 
Otospermophilus Mericanus, Branpr, Bull. Phys. Math, Acad. St. Pet. 1844, 379. 
Gimper, Saugt. 1855, 638. 
Urion & Ardilla, of the Mexicans. 
Size that of S. hudsonius, or larger. Tail vertebra about half the length of body, the outstretched hind feet reaching 
about to its middle Ears short, but distinct. Thumb with a stout rudimentary claw, Central line of the soles hairy 
halfway to end of metatarsus. Color above dark chestnut brown, tinged with olivaceous, with nine to eleven pretty 
distinct longitudinal rows of subquadrate light spots. Tail margined with whitish, within which are two black bands, 
(to three light ones,) the extreme base of the hairs being sometimes dusky in addition. Length, 7 to 8 inches; tail, with 
hairs, 5 to 53; hind feet, 1. 65 inches. 
In size and general characters this species is not very dissimilar to S. 13-lineatus, of which it 
is the more southern representative. The head is shaped much like that of the latter species, 
being somewhat acute, as in Sciwrus hudsonius, and differing considerably from that of Spermo- 
pilus spilosoma. The ears are short though quite distinct, the auricle running longitudinally 
and well covered with hairs on both sides. The feet are well developed ; the claws very long 
and slightly curved. The thumb is armed with a stout rudimentary claw, rather than a mere 
nail, although there is considerable difference in this respect with specimens. The third claw 
is longest ; the fourth rather shorter; the second extending to the middle of. the claw of the 
third ; the fifth to the base of the claw of the fourth. The palms are naked. The claws of the 
hind feet are weaker than those in front; the third is longest; the second and fourth equal, 
and but little shorter ; the first shorter than the fifth, which does not extend nearly to the base 
of the claws of the longest toes. The soles are coated with scant hairs beneath the tarsus and 
part of the metatarsus, principally along the median line. The tail vertebra are about half the 
length of the body, or a little more, and the hairs are much longer than usual in this group, 
much more so than in S. 13-lineatus. The under part of the tail is sparsely covered, and the 
tail exhibits a flattened appearance. 
The upper parts and sides generally are reddish brown or a shade of chestnut brown, some- 
times tinged with olivaceous, the precise tint varying considerably with the specimen, and 
sometimes much overloaded with the black tips to the hairs. This color is relieved by a series 
of longitudinal rows of whitish spots extending from the occiput to the tail; of these there can 
generally be traced four or five on each side of the median or vertebral one, the spots of different 
rows mostly opposite each other ; the intervals between the rows about equal to the spots them- 
selves. In some specimens the narrow intervals between the spots of one series are black, in 
others of the ground color, though always mixed up with black. The spots are more or less 
quadrate, and average, perhaps, the eighth of an inch in size. The hairs are lead color at the 
base ; those occupying the light spots are black immediately beyond the root, and have a short 
black tip, the whitish being subterminal ; interspersed among the brown tipped hairs are many 
that are black throughout. The top of the head is coarsely grizzled with whitish brown and 
black. The eyelids and under parts generally are dull whitish or brownish white, clearest on 
the head. Those posteriorly exhibit a little dusky at the base; anteriorly, however, they are 
unicolored. 
The basal portion of the tail is grizzled not unlike the top of the head ; the terminal portion 
