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U. S. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



List of specimens. 



Collected by Dr. Heermann. 



THOMOMYS LATICEPS, Baird. 



Broad-headed Gopher. 



Thomomys laiiceps, BAIRD, Pr. A. N. Sc. Phil. VII, April, 1855, 335. (Humboldt Bay.) 



SP. Cn. Cheek pouches moderate, well haired. Tail nearly one-half the body, thick at base. Skull very broad and 

 muzzle short ; the upper incisors convex, the groove quite distinct. Feet very large and broad. Claws of fore foot or 

 hand small, slender, 4 lines long above ; below, about two-sevenths the length of the whole hand, its digit about two- 

 eighths. Claw of thumb extending over nearly three-sixths the hand. 



Color. Above, yellow reddish brown ; the dorsal region with the hairs largely and sharply tipped with blackish ; sides 

 nearly uniform ; beneath, tinged with reddish. Pouches dull white, the dusky of the surrounding region dipping into 

 them. Tail grayish white, dusky above. 



This species, with one from the upper Missouri, is eminently characterized among all those 

 with smooth upper incisors by the very broad and powerful feet and larger hands. The ear 

 flap is short though distinct ; the whiskers short and of a grayish color. The fur is soft, silky, 

 and moderately long. The tail is much developed, very thick at the base, and almost half the 

 length of the body, well coated with hair. The pouches are not very large, densely furred 

 inside next the head, more sparsely elsewhere. 



The fore feet are large, especially the palms ; the first finger or thumb is short, though 

 inserted quite far forwards its claw does not quite reach to the middle of the hand, (from wrist 

 to point of claw.) The claws generally are rather small, much curved, and quite slender ; the 

 third projects, on its lower edge, to a distance which is contained about three and a half times 

 in the entire hand, or fths ; its phalanges only about half the length of the palm proper. 

 The second finger and claw are considerably longer than the fourth ; the point of the fifth claw 

 extending more than half the total length of the hand ; the first claw extending as far as the 



