GEOMYIDA2—THOMOMYS TALPOIDES BULBIVORUS. 627 
Hasitat.—Pacific coast and slopes of the United States, from Washing- 
ton Territory to Southern California. 
There is no decided difference in size or shape between this form and 
the last, except an average less development of the fore claws. The extreme 
of the budbivorus branch of this species is readily recognized by a warmth 
and intensity of coloration not known to occur in specimens from the North- 
ern Interior; the color varies a great deal, but is never the clear mouse-gray 
of talpoides, being an intimate mixture of yellowish-brown and dark brown 
or blackish. Above, the pointing of the fur conceals the plumbeous bases of 
the hairs; below, this plumbeous shows, overlaid with a strong wash of tawny 
or muddy-brown, unlike the hoary-gray of the same parts of tadpoides. The 
under surface is not known to be varied with patches of white,* nor is there 
any white about the mouth, excepting the immediate border of the lips; the 
mouth-parts being sooty or dusky, contrasting with the white which lines the 
cheek-pouches. This is very much as in wmbrinus, and quite different from 
talpoides. The fore claws average about 0.40—rather less than more. Such 
typical manifestation of this form I have only seen from California; it changes 
insensibly into both ta/poides and umbrinus. Proceeding up the Pacific coast, 
we find an animal still like dudbivorus in general tone of coloration, but in 
which the mouth-parts have nearly or entirely lost their sootiness; the fore 
claws also enlarge somewhat, and from this state it is but a step to true éad- 
poides, which meets ‘‘dowglasi” in the interior of Oregon and Washington. 
In the interior of California, the opposite modification begins, tending to 
umbrinus, which becomes established in Arizona and New Mexico. Here 
the dark mouth-parts are intensified, but the color grows richer till a decidedly 
tawny or fulvous cast results. Specimens from Fort Crook and Fort Tejon, 
Cal., and from Provo, Utah, are ambiguous, exhibiting much variation. Some 
of the browner ones are inseparable from budbivorus, while the ruddiness of 
others matches that of typical wmbrinus. ‘The intergradation of the two forms 
in this region is complete. Some other specimens from Fort Crook are iden- 
tical with Steilacoom ones in color; the only difference being the weaker 
claws. To the southward, on the coast, the same intergradation occurs, 
becoming established about San Diego. In Lower California, pure umbrinus 
prevails. 
* A San Franciscan specimen is a perfect albino—snow-white all over. 
Pp 
