396 
U. S. P. R. R. EXP. AND SURVEYS-ZOOLOGY-GENERAL REPORT. 
1 Measured before skinning. 
THOMOMYS BOREALIS. 
Geomys borealis, Rich. Report British Asso. for 1836, V, 1837, 156.—(Said here to come from Saskatchewan.) 
Bachman, J. A. N. Sc. Phil. VIII, i, 1839, 103. 
Ascomys borealis, Wagner, Suppl. Schreb. Ill, 1843, 391. 
Pseudostoma borealis, Aud. & Bach. N. Am. Quad. Ill, 1853, 198 ; pi. cxlii. 
Geomys townsendii, (Rich. Mss.) Bach. J. A. N. Sc. Phila. VIII, i, 1839,105. 
Rich. Zool. of Blossom, 1839, 12. 
Ascomys tovmsendii, Wagner, Suppl. Schreber, III. 1843, 391. 
After a careful examination of the specimens in the collection of the Phila. Acad. Nat. 
Sciences, upon which this species was established by Bachman, I have failed to find any satisfac¬ 
tory points of distinction from T. douglassii. These specimens were collected by Dr. Townsend 
on the Columbia river, and were named Geomys borealis and townsendii by Richardson; the latter, 
' however, differing only in the comparative shortness of the stuffed and dried tail. They have 
the same peculiarities of the hands as described in the supposed specimens of T. douglassii , col¬ 
lected by Dr. Suckley at Steilacoom, namely, the very short first finger, the small palm and 
large claws, &c. The points of distinction are essentially in color, G. borealis having the upper 
parts of a bright yellowish brown or rufous, without any mottling of darker, much as in 
T. fulvus of Woodhouse ; this color is replaced on the sides of the body anteriorly, and of the 
head by a dull yellowish grayish ; this color seen also on the outside of the legs and the whole 
under parts, brightest on the belly. The inside of the pouches is of a clearer whitish. The 
tail is grayish white. The specimen labelled Pseudostoma townsendii, is a good deal larger, 
with a shorter tail; the colors above are still paler than in the first mentioned one, with 
less of the red and more yellow on the upper parts, and white beneath. There is a single 
middle patch of hairs, white to the base on the sternal region ; elsewhere they are plumbeous 
at base as usual. The inside of the pouches is whitish, except the upper half of the wall next 
the head, which is plumbeous. The hairs of the pouch are rather thin set. 
I do not feel satisfied, from differences of shade in color merely, to separate specimens as dis- 
