RODENTIA-GEOMYINAE-THOMOMYS UMBRINUS. 
399 
In the absence of specimens of this type of Geomys from the Columbia, especially of the 
originals of Dr. Bachman, I am unable to say whether this is identical or not with G. borealis 
or townsendii, although this is quite probable. That it is the same with the Thomomys rufescens 
of Maximilian I am satisfied, as the description agrees very well with it, the color being only 
more yellowish, and the specimen was collected within the same region with that of Prince 
Max. Richardson, in his report on North American Zoology, in the Reports of the British 
Association, (but nowhere else,) identifies Geomys borealis with the Saskatchewan species, pre¬ 
viously supposed by him to be G. talpoides. Should the question of priority come up between 
borealis and rufescens , after they are conclusively shown to be the same, it must be settled in 
favor of the former, as having been published in the same year, but read by Dr. Bachman before 
the Philadelphia Academy, August 7, 1838, and by Prince Max., at Breslau, January 29, 1839. 
The species was named, but not described, by Richardson himself, in 1837. 
Several specimens of gopher, collected at the mouth of the Yellowstone, by Lieut. Warren’s 
Expedition, agree in general characters, but are smaller. The upper parts are rather light 
yellowish brown, the sides ashy gray; the under part, generally, grayish white ; there is a dusky 
plumbeous tinge about the nose ; the feet and tail are white. 
List of specimens. 
Catalogue number. 
Corresp’g No. of skull. 
1 
Locality. 
When 
collected. 
Whence and how 
obtained. 
| Original number. 
Nature of 
specimen. 
Measurements. 
Collected by— 
& 
| Nose to ear. 
| Nose to occip. 
j Nose to tail. 
j Tail to end of vert. 
| Tail to end of hairs. 
j Length of fore foot, j 
j Length ofhind foot. J 
Length of fore claw. 
Length of skull. | 
610 
1776 
1777 
1758 
: | 
Fort Pierre, Neb. 
Fort Union, Neb. 
1853. 
July 19, 1856 
July 24, 1856 
Dr. J. Evans. 
Lt. G. K. Warren.. 
A 
Skin .... 
”63 
1.13 
1.50 
4.50 
5.00 
2.08 
2.00 
2.12 
2.13 
•84 
1.09 
.33 
1.33 
Dr. F. V. Hayden. 
2512 
Port. Randall. 
Skull.... 
THOMOMYS UMBRINUS. 
Sonora Gopher. 
Geomys umbrinus, Rich. F. B. A. I, 1829, 202.— Ib. Rep. British Assoc, for 1836, V, 1837, 157. 
??Waterhouse, Charles. Mag. N. H. Ill, 1839, 596; fig of skull. 
J. L. Leconte, Pr Ac. N. Sc. Phil. VI, 1852, 162. 
Ascomys umbrinus, Wagner, Suppl. Schreb. IV, 1843, 389. 
Pseudosloma umbrinus, Aud. & Bach N. Am. Quad. Ill, 1851, 307. 
Sp. Ch. —Cheek pouches large, rather sparsely haired on the outer wall. Tail slender, one-third to one-half the length 
of body, dusky all around with a white extremity. Upper incisors convex, the groove obsolete. Hand large ; claws much 
curved, long ; middle claw 5 lines, its under surface occupying more than two-sixths of the whole hand, its digit about 
two-eighths the same length. Claw of thumb reaching more than two-fifths over the hand. 
Cokr. —Above, reddish brown, with a dorsal wash of very dark reddish brown ; paler on the sides and beneath. No 
distinct mottling on the sides. Cheek pouches white inside to the margins ; edges of the mouth all round and chin dark 
sooty brown, contrasting strongly. (No white.) 
In very old specimens, the color above is paler and more gray brown ; beneath, grayish white. 
This species is of rather small size, (judging from the specimens examined,) as compared with 
others of the genus. The body is somewhat slender and depressed. No appreciable neck, but 
the head apparently the termination of the trunk as usual. The fur is soft and silky lustrous.; 
not so soft as in T. bulbivorus. The external ears are distinctly visible as an elevated 
