SCIURIDA.—SPERMOPHILUS SPILOSOMA. 865 
ears are very small, being little more than a thickened rim. Hairiness of the 
soles variable, the soles being in some specimens densely pilose, and in others 
nearly naked. 
This species, in the general color of the dorsal surface, bears some 
resemblance to S. mexicanus, but it is of a lighter reddish, and lacks the dis- 
tinct lines of white spots seen in the latter. It further differs in being smaller, 
in having a much broader and quite differently shaped skull, and in its very 
much shorter tail, which is slender and terete instead of somewhat full and 
distichous. Its nearest ally is S. obsoletus, from which it is but doubtfully 
distinct, differing mainly in its more reddish color and the greater distinctness 
of the white spots. 
This species was first noticed by Mr. Bennett in 1833, who described it 
from two specimens supposed to have come from California, the locality being 
vaguely indicated as ‘that part of California which adjoins Mexico”. The 
specimens were young, the molars being unworn, and the length only five 
inches and a quarter. Wagner, in 1843, thought it doubtfully distinct from 
S. mexicanus. Audubon and Bachman figured for it the young of S. mexicanus, 
and afterward, becoming aware of their mistake, completed the confusion of 
the two species by referring the S. spi/osoma of Bennett to S. mexicanus as a 
synonym of that species! Its claim to distinct specific rank was again first 
asserted in 1855 by Professor Baird, who was able, from his abundant mate- 
rial, to fully make known its true characters and affinities. Although its dis- 
tinctness has since, I think, been unquestioned, no additional specimens have 
been brought to light by recent collectors, so that I find now in the National 
Museum only the material used by Professor Baird, and have seen no other 
‘specimens. It is still apparently rare in collections. 
Its known range extends from Fort Stanton, N. Mex. (Dr. T. C. Henry), 
and El Paso, Tex. (J. H. Clark), to Chihuahua (J. Potts) and Sonora (Dr. 
Kennerly), Mexico. Professor Baird* states that “it occurs abundantly from 
the Gulf of California as far east as El] Paso, and even northward to Fort Stan- 
ton”. He further quotes from Dr. Kennerly’s notes that it was “quite common 
around Janos”, Sonora, “but exceedingly shy”, so that ‘fa specimen was pro- 
cured with difficulty”. 
*Rep. U. S. and Mex. Bound. Surv. vol. ii, pt. ii, p. 39. 
55 M 
