SCIURIDA—SCIURUS HUDSONIUS AND VARS. 683 
brownish-red, and in the central portion of the tail being also dark brownish- 
red, with the enclosing black bar much broader and purer black and more 
narrowly fringed with yellowish. Often the terminal half of the tail is almost 
wholly black. 
Var. douglassi generally differs little in the general color of the dorsal 
surface from var. richardsoni, being, on the whole, rather darker or more 
fuscous. The tail, however, is less black, and is more broadly fringed with 
yellowish-white. The central portion (dorsally) is generally less strongly 
ferruginous, varying sometimes to gray. The ventral surface of the body, 
however, is tawny, thus furnishing, in typical examples, a very obvious 
distinctive feature. ; 
Var. fremonti generally lacks the central dorsal stripe, and the fulvous 
of the upper surface inclines more strongly to yellow. The tail is generally 
gray centrally above (sometimes more or less fulvous or rufous), with a broad 
enclosing zone of black, broadly fringed with pure white. 
These varieties, in their extreme phases, appear very distinct, yet wherever 
their respective habitats meet their characters become very much blended. 
Thus, as already noted, in Northwestern Wyoming, where meet the habitats 
of varieties hudsonius, richardsoni, and fremonti, a considerable proportion of 
the specimens received from this region can scarcely be referred to one of 
the varieties rather than to another. Many of the specimens present distinctly 
traces of the leading characteristics of the three forms; others, while present- 
ing considerable resemblance to hudsonius, incline most strongly to var. 
richardsoni; others, again, toward fremonti. Others still, both from this 
region and from localities much farther westward, combine the leading 
features of vars. richardsoni and fremonti. Specimens from the region where 
the habitats of richardsoni and douglassi meet are again variously intermediate 
between these two forms, being generally distinguishable only by the color of 
the ventral surface. In California, where the habitats of douwglassi and fre- 
monti meet, the same localities furnish typical examples of each form, with 
others variously intermediate between them. Professor Baird, in 1857, with far 
less material before him than has passed under the examination of the present 
writer, in referring to the gray-tailed specimens from California, says :—“In 
this condition the tail exactly resembles, in every respect, that of S. fremonti, 
and the two [S. douglassi and S. fremonti], comparing Nos. 1160 [S. douglass: 
from the Upper Des Chutes] and 520 [S. fremonti from Sawatch Pass, 
