852 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
texture of the pelage, the two are entirely distinct, and, as respects the form 
of the skull, are almost at the opposite extremes of the genus. In coloration, 
S. richardsoni, as represented in some phases of var. townsendi, makes a close 
approach to S. mollis, so that half-grown specimens of the former, in a bad 
state of preservation, might be distinguished with difficulty from S. moldis. 
The two species are, however (as will be shown later), radically different. 
S. richardsoni hence has no very intimately allied American affine. Its rela- 
tionship to some of the Spermophiles of the Old World seems to be somewhat 
closer than to any American species. The coloration of the mottled phase of 
var. townsend: somewhat resembles that of S. guttatus, to which it was referred 
by Richardson and subsequently by other authors, on the ground of Richard- 
son’s description. Audubon and Bachman state that they compared a speci- 
men of their S. townsendi with specimens of S. guttatus in the Berlin 
Museum, and found that though there was “a general resemblance” between 
them, they were “scarcely more alike than the Red Squirrel of Hurope 
(Sciurus vulgaris) and the Red Squirrel of America (Sciurus hudsonius)”. 
They add:— They may be distinguished from each other at a glance by 
the large rounded spots on the back of the Russian animal, compared with 
the white and irregular specks in the American species.” ‘Two examples of 
S. guttatus now betore me sé¢em to fully bear out this latter statement. 
S. richardsoni presents a wide range of geographical variation, but can 
he only rather arbitrarily subdivided into geographical races or subspecies. 
Northern specimens are not only considerably larger than southern ones, but 
are much more fulvous, with a minimum amount of black, and smaller ears. 
The southern form, as contrasted with the northern, is not only smaller, but 
the fulvous suffusion of the northern type is replaced by a ‘reddish- or 0@ hrey- 
brown tint, and there isa great accession of black above, and especially in 
the tail. This form is developed in its most strongly differentiated phase in 
the region where also occurs the richardsoni type of Sciurus hudsonius, a 
reddish-brown phase of Tamias asiaticus, and the smaller dark phase of 
Spermophilus empetra. 
The Pembina specimens, as well as all of those collected thence west- 
ward to the Rocky Mountains, agree perfectly with Sabine’s and Richardson’s 
descriptions of S. richardsoni, based on specimens from localities much fur- 
ther north, The specimens from along the forty-ninth parallel are the palest 
of any before me; others, however, from Fort Ellis, Montana, and from 
