RODENTIA GEOMYINAE GEOMYS CASTANOPS. 



385 



fectly symmetrical in size and shape. The external ears are entirely obselete, with scarcely a 

 thickened ridge of skin to represent the auricle. The tail is contained not quite three times in 

 the body ; it is moderately clothed with stiff appressed hairs of a dusky color. 



The fur is quite sparse though moderately soft everywhere. The cheek pouches are small 

 and not very capacious ; scantily haired within. 



The fore feet are decidedly shorter than the hinder ones ; its claws are moderately large and 

 stout, acuminate near the tips. The third claw, as measured above, does not reach nearly from 

 the end of its digit to the tubercle on the palm ; below, it is scarcely one-third the total length 

 of the hand. From the heel to the end of the first claw is about two-fifths of the whole hand. 

 The second and fourth fingers and claws are of the same length, or the second finger is even 

 the longer ; the fourth claw, as usual, is, however, the stouter. The first claw does not quite 

 reach the end of the fifth finger ; the fifth claw barely to the end of the fourth finger. On the 

 hind foot the toes are cleft quite deeply ; the first is longer than the fifth (the claw of the 

 latter reaching to the middle of the claw of the former) ; the second claw reaches nearly to the 

 end of the third, and is even the longer, besides being very broad and spoon-shaped ; the fourth 

 claw reaches to the end of the second toe. 



The upper parts and sides, generally, are of a pale brownish yellow ; the hairs on the back 

 and thighs slightly tipped with darker yellowish brown, so as to impart a faint shade of this 

 color ; the sides and under parts are rather paler, showing a good deal of the dark plumbeous 

 bases to the hairs. The top, anteriorly, and the sides of the head, are of a pale yellowish 

 chestnut ; this color extending behind the ears in a symmetrical subcircular patch, having the 

 ear as a centre, and a radius of about three-quarters of an inch. These patches are distinctly 

 and sharply defined ; the two on opposite sides separated by a narrow strait, colored like the 

 back. The chin, pouches, and throat are somewhat of the same color, with a few dusky hairs. 

 The region immediately around the ears is rather dusky. 



The only specimen of this species, at present known to naturalists, is the one in the Patent 

 Office, which served as the basis of my description in Captain Stansbury's report. It was col 

 lected by Lieut. James W. Abert, United States army, and is labelled as having been obtained 

 on the prairie road to Bent's Fort, New Mexico. 



49 L 



