RODENTIA—GEOMYINAE—THOMOMYS RUFESCENS. 397 
tinct which are found in the same locality, and which agree in all essential points of structure. 
Ihave noticed almost parallel conditions in 7. wmbrinus, T. bulbivorus, &e. The whitening 
of the under parts may be the effect of age (as larger specimens show it most) or of season. 
Before this question can be definitely settled, it will be necessary to examine many more speci- 
mens of these species than have yet been seen by naturalists. When skulls of 7. douglassii and 
of the supposed lighter borealis can be compared, the question will be nearer a solution. 
Dr. Leconte is probably correct in referring the specimen in the academy, labelled @. Rich- 
ardsonii, to the others above mentioned. In fact, by its darker under parts it approximates 
much closer to the typical colors of douwglassii. The greater length of tail is owing to its 
having been skinned and stretched by thrusting in a sharp stick intended to replace the 
vertebre. An elongation of fully halfan inch can in this way be readily accomplished. The 
chin and pouches are quite distinctly white, in strong contrast with the darker parts around 
them. The colors above are more ashy than in the other two. 
It is quite possible, as Dr. Leconte suggests, that Geomys borealis may be identical with 
Thomomys rufescens. Some remarks on this subject will be found in the article on the latter 
species. 
Since the preparation of the preceding article, Dr. Newberry has collected a small gopher at 
Canoe Creek, California, which, though young, yet differs in some respects from Z’homomys 
bulbivorus in the larger claws, and from both, this and dowglassii, in the much lighter and nearly 
white under parts. The feet and tail are white. If @. borealis be a different species from 
douglassii, this specimen may possibly be referred to it. 
List of specimens. 
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21260 | 2225 | J’ | Canoe Creek, Cal...... Aug., 1855 | Lt. R. 8. Williamson...| Mounted... | 4.20 | 1.65] .80 | .95 | .32 | 1.13 | Dr. Newberry. 
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THOMOMYS RUFESCENS, Maxim. 
Fort Union Gopher. 
Thomomys rufescens, Pr. Maximintan, Nova Acta Acad. C. L. C. XIX, 1, 1839, 383. 
Wircmann’s Archiv, 1841, m1, 42. 
Bairp, Pr. A. N. Sc. Phila. VII, April, 1855, 335. 
Sr. Cu.—Cheek pouches rather small ; densely furred. Tail nearly half as long as the body; thick at base. Upper in- 
cisors very large ; the groove very shallow and obsolete. Feet very stout and broad. Claws of hand stout ; not very long ; 
much curved. Third claw 4 lines long above; beneath, occupying barely two-sixths of the total length; the claw of 
thumb reaching over two-fifths the hand. 
Color.—Above, ashy or grayish yellow brown; sides similar. Beneath, with the pouches‘’and surrounding area, yellowish 
white. Tail whitish ; dusky above at the base. 
This species possesses, in common with the one from Humboldt bay, the characteristics of long 
and thick tail, very powerful fect, and a size of skull apparently disproportionally great, in 
