342 U. S. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



on the upper parts and sides of a pale yellowish hoary, instead of being black. The top of the 

 head is dark brown, except on the muzzle, which is black ; there is, however, a subterminal 

 band of grayish white, as described. The feet and tail are entirely black. The bases of all the 

 hairs in this specimen are almost black. In this, though a male, the teats are distinctly dis 

 cernible to the number of four on each side two on the groin, one inside of the shoulder, and one 

 behind the axilla. There are none visible on the belly. 



We thus see that this species varies very considerably in the color of the lower parts, and to 

 a less extent in the upper ; nor is the color a question of age, as very large specimens are as 

 different as half grown and young ones. The principal variations before me are as follows : 



1. Almost entirely glossy jet black all over. On the back, however, the long hairs have dull 

 yellowish rusty tips. The under fur on the back sooty brown at th*D base, becoming faintly 

 yellowish brown towards the end. Nose and chin whitish. (No. 1572.) 



2. General color dusky. The grizzling of the dorsal surface CDnfined mainly to the sides of 

 the shoulders. Under fur with light brownish yellow tips. A dark rusty or chestnut suffusion 

 round the fore legs. Nose and chin whitish. (No. 847.) 



3. Similar to the last in all respects, but with the black hairs of the belly tipped mostly with 

 dark chestnut. (No. 1571.) 



4. Under parts still more chestnut, though also showing much black ; above, more generally 

 yellowish hoary. A still deeper chestnut tinge round the fore legs. (Nos. 854, 1575, 1574.) 



5. Under parts pretty uniform chestnut, the bases of the hairs still dusky. The hairs around 

 and between the bases of the fore legs brighter and deeper chestnut. (Nos. 1631, 1573.) 



6. Similar to preceding, but the tail is grizzled like the back, the hairs above and below being 

 all finely annulated with brownish yellow, white and dark brown. (Nos. 1392, 1150.) 



As a generalization from these variations, it may be stated that the legs and tail are almost 

 always black, (in 1392 the tail is grizzled like the back.) Where the belly is rusty, the region 

 round the base of the fore legs is of a deeper chestnut. The upper parts are not pure black in 

 any of the specimens before me ; where the dorsal surface is hoary, this is most distinct, and 

 lightest on the sides of the shoulders, as in Spermophilus douglassii and beecheyi. In all the 

 specimens the soles are naked. 



It is worthy of remark that the only specimens enumerated in which the tail is grizzled like 

 the back, with the hairs annulated, are those from Wisconsin and Missouri. 



This species, so familiarly known throughout the United States as the woodchuck, or ground 

 hog, has been described under several names. There is now no reasonable doubt that the 

 Arctomys empetra, so long kept separate from the A. monax, is really identical with it, as 

 insisted on by Audubon and Bachman. According to these authors, the species ranges from 

 Hudson's Bay to South Carolina, and westward to the Rocky Mountains. It is probable, how 

 ever, that at some distance west of the Upper Missouri it is replaced by the species I have 

 called A. flaviveniris. 



