SCIURIDZ—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 intense 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. harrist), 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 cbsence of a black dorsal line. 
With this exception, it has essentially the pattern of coloration seen in T- 
striatus and T. asiaticus. The white stripes begin at the ears and terminate 
at the hips, but anterior to the shoulders they are often much obscured by a 
‘strong suffusion of rufous. In voice, habits, mode of life, pattern of colora- 
tion, and external features generally, 7. /ateralis 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 Tamia. 
This species was first described by Say, in 1823, from specimens ob- 
