SCIURIDA—SPERMOPHILUS MEXICANUS. 869 
the sides; ring surrounding the eye and lower edge of cheeks white; head 
above finely mixed white, black, and yellowish; tail above varied centrally 
with black and yellowish-white, with an indistinct black border broadly edged 
with yellowish-white ; below, brownish-white centrally, with a distinct sub- 
terminal band of black and a broad edging of brownish-white. The hairs 
individually have a narrow black bar at the base, followed by alternate bars of 
brownish-white and black, three of each, the terminal one being whitish. 
This species varies as usual more or less in respéct to general color, that 
of the dorsal surface ranging from dull ashy-brown to chestnut. The num- 
ber of rows of white spots varies from nine to thirteen, but either nine or 
eleven is the more common number, the two or three central ones on either 
side of the median line being generally much more distinct than the outer 
ones. In the latter, the white spots are longer and nearer together, forming 
sometimes an almost uninterrupted line. The ears are very small, but dis- 
tinct. The tail-vertebrz alone are rather more than half the length of the 
head and body; claws long, that of the thumb quite large. Soles nearly 
naked. Pelage coarse and stiff, the hairs mostly grooved above. 
In size and proportions, as well as in the pattern of coloration, this 
species more resembles S. ¢ridecemlineatus than any other, but differs from 
it quite markedly in many details. The tail is longer and more bushy, with 
three narrow longitudinal lines of black beneath instead of one very broad 
one (in addition, there is, however, in S. tridecemlineatus, a narrow basal 
one); the general color above is much lighter and of a quite different shade, 
with interrupted lines of whitish spots instead of six or more narrow, contin- 
uous, yellowish-white stripes, with a similar number of interrupted ones be- 
tween them; there are also well-marked differences in the skull. In respect 
_to cranial characters, however, S. mexicanus finds also its nearest ally in S. 
tradecemlineatus. 
In respect to coloration, there is considerable resemblance between S. 
mexicanus and S. spilosoma; but, in other features, the two species differ 
widely, as already noticed in the account of S. spilosoma. 
This species was first recognizably described and figured by Lichtenstein, 
about 1830, from a specimen collected by Herr I’. Deppe, in July, 1826, in 
the neighborhood of Toluca, Mexico. Erxleben, in 1777, characterized a 
“ Sciurus mexicanus”, based on Fernandez’s description of his “ Téamototic”, 
