304 U. Ss. P. R. R. EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
SPERMOPHILUS, Cuvier. 
Spermophilus, F. Cuvier, Mem. Mus. VI, 1822, 293. 
Aun. & Bacu. N. Am. Quad. I, 1849, 76. 
Spermatophilus, Wacier, Syst. Amph. 1830. 
Citillus, LicHTENSTEIN. 
With the general characters of Arctomyina. Cheek pouches well developed. Pupils oblong (?). No claw to the thumb, or 
else very small. . 
Body more slender than in Arctomys; more or less like the squirrels. Ears variable, well developed or quite diminutive, or 
apparently wanting. External outline of upper molars gently curved ; the inner nearly straight and very slightly diverging 
anteriorly; the anterior and posterior extremities of the line equi-distant. The upper outline of the skull is gently curved; not 
depressed and plane, as in Arctomys; the cranium, too, is narrower and more convex above, and the zygomatic arches: less 
divergent. 
The outer toe of the fore foot scarcely reaches to the middle of the sole, (without the nail,) the tip of the outer claw of fore 
and hind feet does not reach the base of the one adjacent to it. The hairs on the sides of the tail are longer than those above 
and below. 
The genus Spermophilus, as above defined, is a very extensive one, and embraces quite a 
number of subdivisions. Brandt, in the paper above referred to, (page 241,) not improperly 
divides Spermophilus into two sub-genera, Colobotis and Otospermophilus. The first includes all 
the European species, and resembles most closely the true marmots; the latter coming nearest 
to the squirrels, in particular to Tamias. Erecting the prairie dogs into a distinct genus would 
leave the typical Spermophili—species with very short tails and ears and naked soles—entirely 
Old World, such as S. fulvus, rufescens, erythrogenys, mugosaricus, and musicus, inhabitants 
chiefly of the Ural Mountains. The Citilli, or species with short tails, distinct ears and soles, 
hairy on the heel and behind the base of the toes, include S. citillus and guttatus in Europe, and 
possibly S. townsendii, in America; an intermediate group, consisting of species with tails 
longer than either of the above, embraces two species, S. parryi, Rich., and S. eversmanni, 
Brandt; of these the former is abundant in Kamtschatka and the islands of Kadjac and 
Arikamtchitchi, and is likewise found in Arctic America, whence it was first described. If the 
same species be really found in both continents it will be the only instance known of a Rodent 
indigenous to the Old World and the New, excepting, perhaps, the muskrat, Fiber zibethicus, 
which by some authors is stated to occur abundantly in northeastern Asia, although this is 
strongly contested by others. 
The great body of North American spermophiles again belong to Brandt’s section Otosper- 
mophilus, with moderate or very distinct ears; tail resembling that of the squirrels, and, in 
fact, only distinguishable externally by the cheek pouches. None of the otospermophiles are 
found in the Old World, and this fact, in connexion with the other differences, is quite sufli- 
cient, in my mind, to warrant the permanent establishment of Dr. Brandt’s genus. 
The characteristics of the subdivisions of Spermophilus, as given by Brandt, are as follows: 
1. Coxozorts, Brandt.—First upper molar one-half or less than one-half the size of the 
second; sub-trilobed or quadrilobed and with the edge compressed, transverse, sub-oblique, 
tolerably broad, truncate. Second, third, and fourth upper molars with the crowns cuneate- 
triangular, compressed on the inner face, considerably narrowed and acuminate. Central 
ridges sub-equal in length, tolerably elevated, parallel on the outer margin of the crown, on 
the inner, however, approximating at a more or less acute angle. Ears truncate or sub-trun- 
