SCIURID.E— 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. 1051, 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 Cynoiiujs columbianus in its more red- 

 dish coloration, longer and differently colored tail, tmd larger size. In respect 

 to the skulls, aside from the difference of size, the nasals, as a rule, extend 

 further back in C. ludovicianus 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. ludovicianus. 



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 '-Rid- 

 dle-Allen" Narrative of Lewis and Clarke's Expedition* published in 1815, 



*See Dr. Elliott Coues's '• Au Account of the various publications relating to ibe Travels of Lewis 

 and Clarke, with a Commentary on the Zoological Results of their Expedition " (Bull. U. S. Geolog. and 

 Geogr. Survey of the Terr. 2d ser. No. 6, Feb. 8, 1876) for an exhaustive aud useful descriptive summary 

 of the various narratives of the Lewis and Clarke expedition, 



