262 EXPLORATION OF THE CANONS OF THE COLORADO. 
strongly contrasting with the white lining of the pouch. Tail usually more 
or less like the body. 
HABITAT. South Colorado, Southern Utah and Southern Nevada, West 
ern Texas, New Mexico, Arizona, and Lower California to Cape Saint Lucas. 
Southward extension into Mexico undetermined. "Louisiana.'' 
Description (from extensive series from the above localities). No other 
form of the genus varies so much in color as this one. With the increase in 
intensity and richness of coloration of the genus to the southward, there is 
'a corresponding ratio of variation to or from what may be held the normal 
mean. Selecting average samples, as, for instance, some I collected at Fort 
Whipple, Arizona, in 1864-'65, we observe a very rich tawny or fulvous 
pelage, more or less obscured on the back by a blackish area. The under 
parts are of the same color, paler or of about equal intensity, with the deep 
plumbeous bases of the hairs showing. The ears are set in a small blackish 
area ; the face, and, to a less extent, the top of the head, are blackish, with 
or without white spots on the lips or chin, contrasting strongly with the 
white lining of the pouches. The feet are indifferently whitish or dusky ; 
and more or less of the tail is usually colored. 
Other specimens, by the extinction of the blackish dorsal area, become 
nearly concolor all over, and of so rich" a hue as to almost bear the term 
golden-brown. There is a great similarity in many cases to the coloration 
of Jaculus hudsonius or Arv'icola aureola. The best-marked samples of this 
style before me are from Southern Arizona and Cape Saint Lucas, where this 
appears to prevail. Dr. Woodhouse's type of " fulvus" is entirely of this color 
above, with nearly white belly. Specimens from the Colorado Valley exhibit 
another style of coloration in their extreme pallor, from the bleaching of 
fulvous into a pale brownish-yellow, and with whitish belly. A specimen 
from "Sonora" (rather Southern Arizona, as now bounded) is dark-cinnamon 
or chestnut-red, with blackish dorsal area. More northerly specimens tend 
to grayer tints ; but this grayishness has a plumbeous cast, and is suffused on 
the sides with tawny. The belly in these cases is as purely hoary-gray as in 
typical talpoides] and one specimen, from Fort Massachusetts, is exactly rat- 
colored, and indistinguishable from pure talpoidcs, except in being smaller, 
though it is apparently very old. In this specimen, too, the characteristic 
