336 U. 8. P. R. R. EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
This species may be readily distinguished from its nearest representative, S. ludovicianus, by 
its somewhat less size, much shorter tail, which is white (not black) at the tip, weaker feet, &c. 
The prevailing color is not light reddish brown, but rather a liver brown, and the mixture of 
the different colors much finer. The fur generally is much softer. From 8. franklini it differs 
by larger size, much shorter tail, much larger thumb nail, and general colors, exhibiting none 
of the yellowish brown gloss of the upper parts, nor the distinct spotting of black. 
The skull differs materially from that of S. ludovicianus in being shorter and broader, the 
molars more parallel, with other characteristics only distinctly intelligible from a figure. 
Since preparing the preceding description, based upon No. 501, two specimens of a short, 
white-tailed prairie dog have been received from Lieutenant Bryan, which possibly belong to 
the same species. They are quite similar to Captain Beckwith’s specimen in general character, 
the very short tail, &c. This is, however, entirely white for two-thirds its length ; the basal 
third being like the back. The terminal hairs of the tail are pure white, and in none is there 
any annulation of black whatever. The prevailing tint, even in the midsummer specimen, 
lacks the red aspect of C. ludovicianus, the predominant color above being a brownish yellow, 
grizzled with paler, the lower parts a pure brownish yellow. The August specimen is 
darker above, with more black hairs intermixed. The tails of these specimens are more cylin- 
drical than in No. 501; their proportions to the body and colors are also somewhat different, 
and it is quite possible that the two may be really distinct, and that the one from Cooachetope 
Pass belongs to a species which has its headquarters somewhere in the Great Basin. 
Lewis and Clark mention a burrowing squirrel from the plains of the Columbia which 
appears to be a C'ynomys, and may possibly be the same with the species here described ; or, if 
two be indicated, as is quite possible, then the specimens of Lieutenant Bryan might be 
referred to the animal of Lewis and Clark, under the name of columbianus. There are, 
however, important discrepancies between the description of the above authors and the Smith- 
sonian skins not readily reconcilable. Thus: ‘‘the two inner toes of the fore feet are 
remarkably short, and are equipped with blunt nails; the remaining toes on the front feet are 
long, black, slightly curved, and sharp pointed.’’ Here it is uncertain whether the authors 
refer to two inner toes of one foot only, making the first and second,! or, as is most likely, 
whether they mean the innermost one of two, making the inner front toes for each animal. 
At any rate the inner toes are said to be remarkably short and equipped with blunt nails, the 
remaining toes being long. This, if the meaning of the author is to be taken in its precise 
signification, is very different from the species here described, in which the inner toe is quite 
large, and armed with a conspicuous claw, nearly as large as most of the others, instead of 
having a blunt nail. This is, however, a matter of much uncertainty. ‘‘ The under parts are 
of alight brick red, the upper of a brown gray, with a slight tinge of brick red; the long 
hairs of the back of a reddish white.’’ There is nothing whatever of this brick red in the 
skins before me, the under parts being brownish yellow, even in summer specimens. ‘‘ The 
head and body are 12} inches; the tail is 24, flat, depressed, with the hairs inserted on the 
sides, the margin white, the bases of the hairs fox red.’’ (No mention of a black median 
band.) 
Should any of these white-tailed prairie dogs ever show a brick red color, I would have 
little hesitation in referring one of them to the Arctomys columbianus, although, as stated, 
Rafinesque has based his genus Anisonyx upon this interpretation of the meaning of Lewis and Clark. 
