GE0MYID2E— TDOMOMYS TALPOIDES BULBIVORUS. 



G27 



Habitat. — 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 Hie fore claws. The extreme 

 of the bulbivorus branch of this sjiecies 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 talpoides. 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 umbrinus, and epiite 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 talpoides and umbrinus. Proceeding up the Pacific coast, 

 we find an animal still like bulbivorus 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 tal- 

 poides, which meets "doughisi" 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 Tcjon, 

 Cal., and from Provo, Utah, are ambiguous, exhibiting much variation. Some 

 of the browner ones are inseparable from bulbivorus, while the ruddiness of 

 others matches that of typical umbrinus. 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. 



