in 
SCIURIDAX—CYNOMYS COLUMBIANUS., 903 
back and below like the ventral surface. ars and general proportions as in 
C. lcdovicianus, except that the tail is shorter. 
Different specimens, even from the same locality, vary considerably in 
respect to color, the dorsal surface being in some pale reddish, as strong as 
in very pale specimens of C. Judovicianus, and in others with only a slight 
tinge of rufous. The proportion of black hairs also varies greatly, being 
sometimes so abundant as to give a decidedly dusky shade to the whole 
dorsal surface, with the head quite blackish and the tail strongly mixed with 
black, with a narrow, partly concealed, subterminal bar of dusky within the 
terminal white area. The extremes of variation in color thus give rise to 
widely diverse phases, but a large series presents every possible stage of inter- 
gradation between these extremes. The lower surface varies from pale 
yellowish-white to bright yellowish-brown or tawny. 
Although occasionally specimens of C. columbianus are met with that 
present almost exactly the shade of coloration sometimes seen in C. ludovici- 
anus, as a rule the two species are readily distinguishable by coloration alone. 
In C. columbianus, the general color above is ye/lowish-brown rather than 
reddish-brown, with a greater admixture of blackish. C. columbianus also 
averages considerably smaller (nearly two inches shorter in head and body 
length), and has relatively a very much shorter and differently colored tail, 
it heing only about one-half as long as in C. dudovicianus. 
As already stated, this species, like the preceding, was first discovered 
by Lewis and Clarke, and-was first named by Ord, in 1815, from the descrip- 
tion of it given in the “ Biddle-Allen” narrative of their journey. | Rafinesque, 
two years later, founded his genus Anisonyx on a misinterpretation of Lewis 
and Clarke’s description, and renamed the species Anisonyx brachiura, Ord’s 
prior name was either overlooked or ignored by subsequent authors (Harlan, 
Richardson, and several foreign compilers), who, however, while adopting 
Rafinesque’s specific appellation, referred the species to Arctomys. ‘Their 
accounts are either simply a quotation of, or a compilation from, Lewis and 
Clarke’s description. Audubon and Bachman, in 1853, renamed the species 
Arctomys lewisi, basing their description on a specimen in the Museum of the 
Zoblogical Society of London labelled “Arctomys brachyura? Harlan”, and 
said to have come from the Plains of the Columbia. Audubon and Bachman 
found, as they thought, sufficient discrepancies between the specimen 
described by them and Lewis and Clarke's description to warrant them in 
