SCIURIDH—~CYNOMYS LUDOVICIANUS. 893 
what harsh, and rather stiff, with very little under fur, particularly at the south- 
ward. Autumnal specimens (including some taken as early as August 23), 
on the other hand, have a very full, soft pelage, with an abundance of whitish, 
very fine, silky under fur. The hairs of the dorsal surface are generally black 
_at the extreme base, then very broadly ringed with whitish or grayish-white, 
followed by a broad zone of reddish-brown, with the extreme tips of the hairs 
whitish. There are also intermixed, sometimes sparsely, sometimes abun- 
dantly, longer hairs, generally wholly black to the base. These are some- 
times so abundant as to give a blackish cast to the dorsal surface, particularly 
on the top and sides of the head and sides of the neck. The color also varies 
somewhat with season, specimens taken late in autumn being more hoary 
above and more fulvous on the sides and below than those taken in early 
summer. Between specimens in winter pelage from the north (Fort Ran- 
dall) and those in summer pelage from the south (Kansas, Colorado, and 
Texas), the difference in the color and texture of the pelage is very striking. 
In the northern specimens, the pelage is full, very soft and silky, yellowish- 
brown, rather strongly varied with dusky; in the southern specimens, the 
pelage is shorter and harsher, brownish-red, varied with intense shining black. 
In some examples (as No. 1651, from Fort Chadbourne, Texas, and No. 9557, 
from Soda Springs, Colo.), the color is nearly brick-red. There is also con- 
siderable variation in size with locality, there being a strongly marked decline 
southward, as shown by the subjoined tables of measurements. 
The present species differs from Cynomys columbianus in its more red- 
dish coloration, longer and differently colored tail, and larger size. In respect 
to the skulls, aside from the difference of size, the nasals, as a rule, extend 
further back in C. dudovicianus than in C. columbianus, and the zygoma is 
thicker and narrower, in strong contrast with the broad, thin plate seen in C. 
columbianus. By size alone, large skulls of C. columbianus cannot be cer- 
tainly distinguished from small skulls of C. dudovicianus. 
This species, like the following, was first brought to the notice of nat- 
uralists by Lewis and Clarke, who met with it on the plains of the Upper 
Missouri during their journey from Saint Louis to the Rocky Mountains and 
the Pacific Ocean, in 1804, 1805, and 1806. In the first volume of the “Bid- 
dle-Allen” Narrative of Lewis and Clarke’s Expedition,* published in 1815, 
*See Dr. Elliott Coues’s “ An Account of the various publications releting to the Travels of Lewis 
and Clarke, with a Commentary on the Zodlogical Results of their Expedition” (Bull. U. S. Geolog. and 
Geogr. Survey of the Terr. 2d ser. No. 6, Feb. 8, 1876) for au exhaustive and useful descriptive summary 
of the various narratives of the Lewis and Clarke expedition. 
