RODENTIA-S ACCOM YIN AE-—PEROGNATHUS FLAVUS. 
423 
Skin mounted , from alcohol. 
Measurement. 
Inches. 
Nose to eye_'_ 
• ear ___ 
occiput______ 
root of tail ______ 
Tail, from root to end of vertebras, (tip broken). 
Ears, height posteriorly____.... 
internally above notch__ 
width. ......... 
Arm, longest claw ...___ 
Leg, hind foot from heel to end of claws_ 
longest claw.... 
Skull, length...... 
width... — ---- 
.46 
.92 
1. 08 
3.00 
2. 67+ 
. 25 
.21 
.14 
.80 
. 12 
.98 
.50 
I unhesitatingly referred this animal to the Perognathus fasciatus of Maximilian, until 
the reception and examination of specimens more nearly allied to the latter. On a careful 
comparison, however, I find that the differences are sufficient to warrant a specific separation. 
The ears are much smaller—scarcely half the size—although distinctly lohed; the feet and tail 
perhaps longer in proportion. The upper parts are much darker; the sides lack the conspicuous 
pale stripe. The belly hairs are plumbeous at the base, instead of pure white; and the dark colors 
of the hack extend on the outside of the fore leg to the wrist, instead of being pure white. 
The skull, though about the size of that figured by Maximilian, is much more mature, the 
tubercles having disappeared entirely. 
List of specimens. 
Catal’gue 
number. 
Correspond!’g 
No. of skull. 
Sex and 
age. 
Locality. 
When 
collected. 
Whence obtained. 
Nature of spe¬ 
cimen. 
Collected by— 
451 
1585 
9 
West of Rocky Moun¬ 
tains, St. Mary’s. ? 
1853. 
Governor I. I. 
Stevens. 
Mounted. 
Dr. Geo. Suckley. 
PEROGNATHUS ELAYUS, Baird. 
Perognathus flavus , Baird, Pr. A. N. Sc. Phila. VII, April, 1855, 332. 
Sp. Ch.—C onsiderably less than the common mouse. Tail equal to or less than the head and body, scarcely different in 
color above and below. Hind feet short. Above, yellowish buff, with dusky tips to some of the hairs; clearer on the sides; 
Beneath, snowy white to the roots of the hairs. Fore leg white to the shoulders. Hairs on the back plumbeous only on their 
basal half. 
This species is almost as diminutive as the P. parvus of Peale, although different in color 
and proportions. The ears are moderately large; the third claw of the hand longest; the 
fourth scarcely shorter; the second reaching to the middle of the third; the fifth extending 
