1855.] 335 



4 4-12ths inches. Tail to end of vertebrae 5 8-12ths inches ; of hairs G 2-12ths 

 inches. 

 Collected by Lt. Trowbridge near San Diego, or Monterey. 



Lt. A. W. Whipple. 



Geomys BREvicEPs, Baird. Upper incisors with a small longitudinal groove 

 near the inner edge, and a much larger one bisecting the remaining space. Fore 

 feet decidedly longer than the hinder, their second claw reaching only to the 

 middle of the fourth. Cheek pouches ample. Skull short, broad. Forehead 

 plane, outlines of zygomata seen from above, curved, widest apart at the junction 

 of the malar and temporal bones. 



Color. Above dark chestnut brown, with dark clouding, caused by the deeper 

 colored tips of the hairs. Beneath paler, mixed with grayish. Inside of pouches 

 and surrounding region entirely yellowish white. Head and body 6| inches. 

 Tail 2 2-12ths inches. Fore feet 1 H-12ths inches. Middle claw 6 lines. Skull 

 1.55 inches in length ; width .98, or 631-100 of length. 



Collected at Morehouse Parish, La., by James Fairie, Esq. 



Thomomys bottle. Oryctovtys bottcs, Eyd.and Gerv Specimens of this species 

 were collected by Lt. Trowbridge and Mr. R. D. Cutts, at Monterey and San 

 Francisco. 



Thomomys rufesckns, Max. Collected at Fort Pierre by Dr. J. Evans. 



Gov. I. I. Stevens. 



Thomomys laticeps, Baird. Cheek pouches moderate, well lined with hairs. 

 Tail nearly half the length of the body, thickened at the base. Feet very large 

 and broad, claws of the hand small, slender ; the middle one measured below is 

 about two sevenths the length of the entire palm, including the claws ; its finger 

 about two eighths. Claw of the thumb extending to nearly the middle of the 

 hand. Skull very broad ; muzzle short. 



Color. Above yellowish red-brown ; the hairs on the dorsal region largely 

 and abruptly tipped with blackish. Sides nearly uniform. Beneath tipped with 

 reddish. Pouches dull white, the dusky tint of the surrounding portions dip- 

 ping into them. Tail greyish white, dusky above. Head and body 5 2-l2ths 

 inches. Tail 1\ inches, short haired portion 1 ll-12ths inches. Fore foot 11^ 

 lines; longest claw 4 lines. Skull 1 l-12th inches broad. 



Collected at Humboldt Bay by Lieut. Trowbridge, U. S. A. 



Lieut. A. W. Whipple. 



Neotoma occidentalis, Cooper, Mss. JV. drummondii, Aud. and Bach. Size 

 of Norway rat. Fur coarse, harsh, not compact. Posterior third of soles furred. 

 Tail densely coated with long hairs ; the vertebrae rather longer than the body, 

 exclusive of the head. 



Color Above brownish plumbeous, with a slight mixture of yellowish brown. 



Under portion of body and tail, with the feet, bluish white. Upper surface of 

 tail grayish plumbeous, the basal wool little lighter. Head and body 10 inches. 

 Tail vertebrae 8 5-12ths inches. 



Collected at Shoalwater Bay, W. T., by Dr. J. G. Cooper, 



Gov. I. I. Stevens, 



Reithrodon montanus, Baird. Size about half that of the common mouse. Ears 

 smaller ; densely furred, and almost buried in the long hairs of the body. Tail 

 about as long as the body ; quite densely coated with short hairs. 



Color. Above, brown and pale yellowish gray ; beneath, dull whitish ; flanks 

 and outside of the ear, pale yellowish brown ; no rufous any where. Tail 

 whitish, dusky on the upper surface. Head and body 2 2-12ths inches. Tail 2 

 inches. Hind foot from heel 6 lines. Skull 9* lines. 



Collected in the vicinity of the Rocky Mountains, iat. 38. 



Lieut, E, G. Beckwith. 



Hesperomys boylii, Baird. Nearly as large as H. gossypinus. Ears very 

 large, so scantily clothed with short hairs as to appear nearly naked, Tail con> 



