SCIURIDA—TAMIAS. 781 
small as it is in 7. asiaticus, and is sometimes wholly wanting, as in skull No. 
4239, from Cape Saint Lucas. In 7. /ateralis, the first of the two upper 
premolars is as large as in some of the Spermophili, the dentition is lreavier 
than in the other Tamia, and in other cranial features this species is about 
as well referable to the one group as to the other. 7. asiaticus has, as already 
intimated, two upper premolars, but the first is very small and slender. 7. 
striatus has but a single upper premolar, and the muzzle is narrower and more 
pointed than in either of the other species. 
The coloration of T. /ateralis is quite similar in pattern to that of T. 
striatus and T. asiaticus, namely, an alternation of dark and light longi- 
tudinal stripes on the dorsal surface. 7. harrisi, however, has only the white 
stripes. In respect to pattern of coloration, we have the following transition 
from T. harrisi to T. asiaticus: —T. harrisi has simply a single longitudinal 
white stripe on each side of the median line of the back; 7. /ateralis has 
the same stripes in the same position, but they are bordered on each side by 
a stripe of black, that on the outer side being usually much the broader; 
T. striatus has the two white stripes, bordered on each side by a broad line 
of black, the outer of which is the wider, with, in addition, a narrow median 
line of black. There are thus five black stripes and two white ones, the 
spaces between the inner black lines being gray. In T. asiaticus, these spaces 
are white or whitish, thus making in this species four white stripes, instead 
of two, which alternate with black ones of about the same width. The 
number of stripes thus increases from simply two white ones in 7. harrisi 
to four white ones and five black ones in TJ. asiaticus. None of the true 
Spermophili are thus marked, although some have interrupted lines of white, 
as S. tridecemlineatus and S. mexicanus. In all the species of Tamas, the 
general color of the dorsal surface is gray, with the sides and sometimes the 
rump washed with rufous. 
In both JT harrist and T. lateralis, the tail is much shorter than in the 
other forms of Tumias, while T. harisi differs from all the others in its much 
smaller ears. Externally, however, there is not only a general similarity in 
the pattern of coloration, but also in general form, while in cranial charac- 
ters there is also a strong degree of similarity, these species agreeing in cer- 
tain common cranial features, by which they are distinguished from the 
restricted Spermophili.* 
* Tamias lateralis is, however, almost an exception, its cranial characters perhaps rather better 
agreeing with one of the sections of Spermophilus than with Tamias. 
