SCIURIM3— TAMIAS LATERALIS. 815 



9820. from Yellowstone Lake (taken in July), is very strongly colored through- 

 out. The whole upper surface and sides of the head and neck are bright 

 reddish-brown, passing into brownish-yellow on the throat and breast. The 

 light stripe on either side of the back is yellowish-white, the dark ones intense 

 black, and of about the same width as the light stripe by which they are 

 separated. The middle of the back is yellowish-gray ; the sides of the body 

 dull brownish-yellow; the lower parts are strongly yellowish, and the tail is 

 edged with the same color. Another specimen (No. 2748, Coll. M. C. Z.), 

 from Montgomery, Park County, Colo., is nearly as strongly rufous as the 

 last, but the back of the neck is gray, like the back. The inner black dorsal 

 stripes are obsolete ; the outer is short and broad, and dull blackish instead 

 of inte.ise black, as in No. 9820. Several others, from the same locality, are 

 very much paler; they show very little brownish on the sides of the neck 

 and head ; the light stripes are well defined and extend from the ears to 

 the hips, but the black stripes are wholly wanting in one specimen (which has 

 hence exactly the pictura of T. harrisi\ and in others only the outer are pres- 

 ent, and are reduced to a short dusky band. Generally, when the inner black 

 stripe is wanting, the outer is double the width it usually has when both are 

 present. Some specimens show no more rufous on the head than elsewhere, 

 except over a small area on the forehead. 



In this species, there seems to be very little variation in color with age, 

 and I am unable to correlate any variations with differences of locality. Some 

 of the most diverse examples were obtained at Montgomery, Colo., the series 

 obtained there by myself in 1871 representing nearly the whole range of 

 variation in the whole series. 



Tamias lateralis is the largest species of the genus, and is easily distin- 

 guished by its coloration, especially by the absence of a black dorsal line. 

 With this exception, it has essentially the pattern of coloration seen in T. 

 striatns and T. asiaticus. The white stripes begin at the ears and terminate 

 at the hips, but anterior to the shoulders they are oflen much obscured by a 

 strong suffusion of rufous. In voice, habits, mode of life, pattern of colora- 

 tion, and external features generally, T. lateralis is a true Tamias, differing 

 from the other species mainly in the larger size of the first upper premolar. 

 This tooth, however, is still much smaller than in the Spermophili. The 

 skull, however, is rather broader and deeper than in the other Tamice. 



This rpecies was first described by Say, in 1823, from specimens ob- 



