208 BULLETIN NO. VII. 
of fine grass. It is notso securely built as the nests of some of 
the other species of this family. Cooper’s mouse lives in winter 
chiefly upon the stems of blue grass and the more tender por- 
tions of white clover. In November, 1883, a large quantity of 
the tuberous roots of the ‘‘ Wild Artichoke” (Helianthus doro- 
micoides) were found in the storehouses of a colony of these 
mice. 
GENUS ONYCHOMYS, BaIrp. 
MOLE MICE. 
This genus is of particular interest in as much as it contains 
three varieties of mice which, from their inaccessible station 
and secluded habits have seldom gained admittance to natural 
history museums or received the attention of naturalists. This 
interest is enhanced by the fact that the genus is evidently 
very closely allied to Vesperimus but has developed in a direc- 
tion entirely different from that group ; and its species, exter- 
nally and in habits, vary greatly from the deer mice. Fossorial 
prairie or desert animals living largely on insects might be 
expected to differ greatly from such saltatorial and gramnivor- 
ous animals as Vesperimus contains. 
The mole mice are distinguished from their relatives by the 
compact arvicoline form, short tail and hind legs, well de- 
veloped anterior extremities with fossorial claws, and the soft 
mole-like character of the pelage. The hasty observer would 
refer the animal to Avrvicoline rather than to the sigmodont 
Murine ; indeed prince Maximilian, who was the first to meet 
the genus, referred the O. lewcogaster to Hypudeus. As we 
have specimens of none of the genus except O. leucogaster var. 
pallidus the reader is referred to the discussion of that variety 
for a description of the anatomical peculiarities. It seems 
that, in view of the many points of divergence in structure and 
habits, there should be no hesitation in separating the mole 
mice genericaliy from Hesperomys. 
Onychomys leucogaster MAXIMILIAN. 
MISSOURI MOLE-MOUSE. 
Hypudeus leucogaster MAXIMILIAN, Reise in das Innere N. America, 1841. 
Mus nrissouriensis AUDUBON AND BACHMAN, Quad. N. A., 1851. 
Hesperomys (Onychomys) leucogaster BAIRD, Mam, N. A., 1857. 
CovuEs, Proc. Acad. Nat. Sci. Phila., 1874; Monogr. N. A. 
Rodentia, 1877. 
Hesperomys leucogaster MAXIMILIAN, Arch. f. Naturg. xviii, 1862. 
