708 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
GEOGRAPHICAL VARIATION.—The principal features of geographical vari- 
ation presented by this species have already been described in characterizing 
the three varieties Jeucotis, carolinensis, and yucatanensis, they cousisting 
mainly in decrease in size southward and an increase in inteusity of coloration, 
the whitish tips of the hairs of the dorsal surface seen in northern specimens 
being replaced by yellowish-brown in the southern ones, except in the case 
of var. yucatanensis. As happens, however, in numerous other instances, the 
largest size is not reached on the Atlantic coast, but far in the interior, toward 
the Upper Missouricountry. Although not ranging much above the Platte, the 
same influences are present, generally in less degree, in Wisconsin and Iowa. 
Thus, a series of seven specimens from Fort Des Moines, lowa, average 11 
inches in length of body, while a similar series from the vicinity of Chicago, 
Ill., fall below 10.50. A series of eleven from the vicinity of Washing- 
ton scarcely reach 10.00, while Florida specimens average only about 959. 
In respect to the Atlantic coast region, few adult skulls from north of Wash- 
ington, D. C., fall below 2.40 in length, ranging from 2.35 to 2.52, while of 
six skulls from the Gulf States, only one reaches 2.30, the average being 
about 2.25. 
Aside from the variation in color with locality already mentioned, speci- 
mens from New England and Pennsylvania can generally be easily distin- 
guished from those from west of the Alleghanies, especially from Ohio, Illi- 
nois, and Iowa specimens, the former being of a clearer or whiter gray than 
those from corresponding latitudes in the West. Specimens from North- 
eastern Mexico are less suffused with fulvous than United States specimens, 
while a still grayer type occurs in Yucatan. As already noted, in Southern 
Mexico the species maintains the feature of excessive fulvous suffusion met 
with in the United States. 
SyNONYMY AND NOMENCLATURE.—The earliest available specific name for 
this species is carolinensis, given by Gmelin, in 1788, to Pennant’s “Lesser 
Gray Squirrel” of Carolina. Pennant’s ‘Quadrupeds” is the only work 
cited, and the habitat is distinctly given as Carolina. In separating the spe- 
cies into northern and southern races, carolinensis must of course be retained 
as the varietal name of the southern form. In 1792, Schreber renamed the 
species cinereus, his description being based on specimens from New York, 
hence referring to the northern variety. The name, however, was preoccu- 
pied, having been previously given by Linnzeus to the Fox Squirrel. Many 
