294 



U. 8. P. R. R. EXP. AND BURVEYS ZOOLOGY GENERAL REPORT. 



brown, darker anteriorly, and on the thighs melting into the chestnut described. The whole 

 under parts, with the upper lip, are pure white to the roots of the hair. The internal surface 

 of the ears is grayish white, except on the anterior margin, which, with the external portion, 

 are like the adjacent region. There is a downy white spot at the base of the ears postero- 

 internally. 



The prevailing colors of the upper surface of the tail are grayish white and black ; of the 

 under surface a uniform light yellowish brown, (darker at the end of the tail,) bordered and 

 tipped, first with black and then grayish white. On flattening the tail above there is seen, 

 first a narrow black line on either side of the skin covering the vertebrae, then a broader one of 

 quite light yellowish brown, then another of black, of nearly equal width, and, finally, a 

 margin of grayish white ; towards the tip the subterminal black increases in extent. 



The specimen described was a female, with the mammae much developed. Of these there 

 are four pairs : two in the groin, one on the sides, and one behind the axillae. Those on the 

 same side are situated a little closer and closer to each other from before backwards. 



The cheek pouches are very large and extend back as far as the shoulder. The opening is 

 wide and situated along the.anterior edge of the buccal muscle. The pouches consist of a very 

 thin naked sac, separating the skin from the muscles of the jaws and firmly attached to both ; 

 their opening is anterior to the teeth in either jaw. 



Fresh measurements of No. 842. 



This species preserves quite a remarkable constancy of character throughout, but little varia 

 tion being discernible in a large number of specimens. One (1559) from Essex county is con 

 siderably grayer, and the black lines of the back have no brownish margin. In a specimen 

 from Washington the chestnut tints are darker than described above. I am told that entirely 

 black varieties are occasionally met with. In the case of the Siberian ground squirrel there 

 appears to be a permanently black variety, known as Tamias uthensis. 



A simple comparison of skins of the European and American striped squirrels, which I have 

 recently been enabled to make, is sufficient to show the radical difference between the two. The 

 former is the larger animal ; the tail is longer, considerably more bushy, and cylindrical. 



