NATURAL SCIENCES OF PHILADELPHIA. 137 



Char, mediocr. Coloration stronger than in the foregoing 

 general cast reddish-brown, lined with dusky on the back, the 

 head usually darker than the rest of the upper parts ; on the sides 

 the color giving way to a clearer tawny-brown, which also occu- 

 pies the bell}', there overlying the plumbeous roots of the hairs as' 

 a strong wash. Face and mouth parts dusky, or even sooty, 

 blackish, contrasting with the white lining of the cheek pouches. 

 No pure white on the under parts. Tail and feet usually incom- 

 pletely whitish, or quite dusky. If anything, averaging rather 

 larger than true tatyoides. Hand rather shorter than the foot, 

 owing to less development of the claws, the longest of which is 

 only about 0.40 long. 



Hab. Pacific slopes and coast of the United States from Washing- 

 ton Territory to Southern California. In the north shades directly 

 through " douglasii" into typical talpoides, and in the opposite 

 direction intergrades completely with nmbrinus. 



lb. Thomomys talpoides umbrinus (Rich.), Coues. 



Oeomys umbrinus, Rich., F. B. A. i. 1829, 202. ("Louisiana,.") 

 Ascomys umbrinus, Wagn., Suppl. Schreb. iii. 1843, 389. (Compiled.) 

 Pseudostoma umbrinus, A. & B., Q. N. A. iii. 1854, 307. (Compiled.) 

 Oeomys {Thomomys) umbrinus, Gieb., Sang. 1855, 530. (Compiled.) 

 Thomomys umbrinus, Bd., M. X. A. 1857, 399. 

 Geomys fulvus, Woodh., these Proceedings, 1852, 201. 

 Pseudostoma {Oeomys) fulvus, A. &B., Q. K A. iii. 1854, 300. (Com- 

 piled. ) 

 Thomomys fulvus, Bd., M. N. A. 1855, 402. 



Char, mediocr. Averaging decidedly smaller than either of the 

 foregoing. Length of head and body little over six inches. Fore- 

 feet averaging decidedly less than the hind feet ; longest claw 

 oftener under than over 0.40. Color varying from a nearly uni- 

 form rich fulvous, or even intense reddish-chestnut, to various 

 tawny-brown shades, with or without a blackish dorsal area. 

 Belly usually merely a paler shade of the color of the upper parts, 

 or much as described under bulbivorus. Occasionally quite gray, 

 as a typical talpoides. (Varies also to a lustrous coal-black all 

 over.) Mouth parts and often whole face blackish, except some- 

 times just around the mouth, sharply contrasting with pure white 

 lining of the pouches. Tail usually not white. 



Hab. S. Colorado, S. Utah, S. Nevada, W. Texas, all of New 

 Mexico, Arizona, and Lower California to Cape St. Lucas. South- 

 ward extension into Mexico undetermined. " Louisiana." 

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