708 MONOGRAPHS OF NORTH AMERICAN RODENT1A. 



Geographical variation. — The principal features of geographical vari- 

 ation presented by this species have already been described in characterizing 

 Hie three varieties leucotis, carolinensis, and yucatanensis, they consisting 

 mainly in decrease in size southward and an increase in intensity 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 Missouri country. 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, Iowa, average 11 

 inches in length of body, while a similar series from the vicinity of Chicago, 

 111., fall below 10.50. A series of eleven from the vicinity of Washing- 

 ton scarcely reach 10.00, while Florida specimens average only about 9 50. 

 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 cinercus, 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 Linnaeus to the Fox Squirrel. Many 



