114 ZOOLOGY. 



blackish like that of the face, which tends to form an obscurely indicated 

 dorsal stripe, but spreads and blends so completely with the chestnut that 

 special marking- is hardly recognizable. The same rich reddish of the sides 

 occupies with little diminished intensity all the under parts ; but here it is 

 confined to a narrower space at the ends of individual hairs, so that the 

 dark leaden-gray of the basal parts of the hairs shows through and inter- 

 rupts the continuity of the chestnut. The tail is of an indefinite dark color, 

 sometimes whitening toward the end. The upper surfaces of both fore and 

 hind feet are whitish, or quite purely white, in decided contrast with the 

 body-colors. 



In the other extreme, of grayness, with the same sooty-blackish face 

 and wash on the upper parts, and the same white pouch and feet, the body- 

 colors are notably different in lacking nearly all of the rich, ruddy-brown 

 tints, which are chiefly apparent along- the sides, especially of the head and 

 chest. The upper parts are gray, obscured with sooty, faintly relieved with 

 a rufous tinge ; the under parts are hoary -gray, showing the darker leaden- 

 gray of the basal part of the fur, and faintly tinged with brownish on the 

 belly. 



The third specimen, like others we have examined, is exactly interme- 

 diate between the extremes above noted. The significance of these differ- 

 ences remains to be ascertained. Professor Baird considered the gray state 

 to be indicative of old age ; season and sex may also influence the colora- 

 tion, or much of the difference may be purely fortuitous. 



The species appears to be abundant in the region where these speci- 

 mens were procured. It is not necessary to suppose that Richardson's type 

 came from anywhere in the State of Louisiana as at present mapped. 

 "Louisiana" was formerly a very vague term, covering much ground, 

 especially upon the labels of specimens of natural history. 



NOTE. Since the foregoing description was penned, Major Powell's Keport of 

 the Exploration of the Colorado Eiver has appeared, containing Dr. Coues's monograph 

 of Geomyidce, which may be consulted for farther accouot of the character ami rela- 

 tionships of this form of Thomomys. 



