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SACCOMYIDZ—PEROGNATHIDINA—C. PARVUS. aly) 
CRICETODIPUS PARVUS, Baird (and Peale?). 
Least Pocket-mouse. 
? Cricetodipus parvus, PEALE, U. 8. Expl. Exped. 1848, 53, “ pl. 13, f. 2”.—GreBet, Siiug. 1855, 600 (compiled 
from Peale).—Gray, P. Z. 8. 1868, 203 (compilation of doubtful references). 
? Perognathus (Cricetodipus) parvus, AuD. & Bacu., Q. N. A. iii, 1854, 328 (copied from Peale). 
Perognathus parvus, BatrD, M,N, A. 1857, 425 (based on a specimen from King’s River, Cal., doubtfully re- 
ferred to C. parvus of Peale).—Barmp, P. R. R. Rep. x, 1859, Williamson’s Route, 82 (samo 
specimen). 
Cricetodipus parvus, COUES, Proc. Phila. Acad. 1875, 303 (monographic). 
Otognosis longimembris, COUES, Proc. Phila. Acad. 1875, 305 (provisional name). 
Diaenosis.—Quite like C. flavus; tail and feet longer. Hind foot 0.70 
or more, one-third or more as long as head and body. Tail decidedly longer 
than head and body; the vertebra about 2.50 inches to a body of 2.00. 
Hasrrat.—United States, west of the Rocky Mountains. California, 
Utah (and ?Oregon, Peale). 
Of this supposed species, I have two specimens additional to the 
material in Professor Baird’s hands in 1857. One of them, alcuholic, in good 
preservation, enables me to give the dimensions with accuracy. 
(No. 9856, Mus. Smiths. Inst. ¢; Fort Tejon, Cal, J. Xantus.) Nose 
to eye 0.45, to ear 0.70, to occiput 0.90, to tail 2.00; tail vertebrae 2.50, with 
hairs 2.75 ; fore foot 0.25; hind foot 0.70; ear above notch 0.25. 
Another specimen, from Utah (No. 439, Mus. Smiths. Inst., formerly 
referred by Baird to C. flavus), seems to belong to C. parvus; the hind feet 
are still longer—nearer 0.80 than 0.70—and the tail at least as long as in 
No. 9856. 
A third specimen, recently collected by Mr. H. W. Henshaw in Califor- 
nia, seems to be unquestionably referable to this species. These three are 
all I have seen. 
As well as can be judged from the insufficient material before me, this 
species does not differ materially in color from C. flavus ; and in fact the only 
diagnostic characters at present appreciable are the greater length of the hind 
feet and tail. There is, however, a decided difference in these respects. 
Further material will be required to confirm the specific distinctness here 
accorded, or to show that the two supposed species intergrade. Leaving this 
matter, we may turn to the history of the species, some points of which call 
for remark. 
In the first place, it is not certain that the animal called parvus by Baird 
