RODENTIA GEOMYINAE THOMOMYS RUFESCENS. 



397 



tinct which are found in the same locality, and which agree in all essential points of structure. 

 I have noticed almost parallel conditions in T. umbrinus, T. bulbivorus, &c. 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 T. 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 G. Rich- 

 ardsonii, to the others above mentioned. In fact, by its darker under parts it approximates 

 much closer to the typical colors of douglassii. The greater length of tail is owing to its 

 having been skinned and stretched by thrusting in a sharp stick intended to replace the 

 vertebras. An elongation of fully half an 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 Thomomys 

 bulbivorus in the larger claws, and from both, this and douglassii, in the much lighter and nearly 

 white under parts. The feet and tail are white. If G. borealis be a different species from 

 douglassii, this specimen may possibly be referred to it. 



List of specimens. 



THOMOMYS RUFESCENS, Maxim. 



Fort Union Gopher. 



T/tomomys rufescens, Pr. MAXIMILIAN, Nova Acta Acad. C. L. C. XIX, i, 1839, 383. 

 WIEGMANN'S Archiv, 1841, n, 42. 

 BAIKD, Pr. A. N. Sc. Phila. VII, April, 1855, 335. 



Sp. CH. 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 feet, and a size of skull apparently disproportionally great, in 



