RODENTIA—SACCOMYINAE—PEROGNATHUS FLAVUS, 423 
Skin mounted, from alcohol. 
Measurement. Inches. 
INGROIO ON Gino ae =e Ann oe oo SE ae ie ee ad - 46 
GOWN Sander sce GSES one Snes A ee - 92 
QCOPULS saciceemon nan acascb eases aenccecdnce 1. 08 
MOCIOM thle ose soos omnes eee Ronee tcecssns 3.00 
Tail, from root to end of vertebra, (tip broken)_----- 2. 674+ 
Bars, height posteriorly. 222. 22.6.- seas 1e5-65-04 ~ 25 
internally above notch _.---------.----- +25 
Vel eee ee ee any ee ne Ve a awe PP 
Arm longest claws <cor-<00- cb sacesoodacec en ekeees 14 
Leg, hind foot from heel to end of claws------------- - 80 
longest claw ojonnaccnecccucscacacewcuscsscces 12 
Skule lenritacsasee ates se cceie fac ee ee eee ee -98 
Width 2.25 Ss50s¢ = SSIS tS esse AS - 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 lobed ; 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 back 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|Correspondi’g| Sex and Locality.” When Whence obtained. /Nature of spe-| Collected by— 
number.) No. of skull. age. collected. cimen, 
451 1585 Q West of Rocky Moun- 1853. Governor I. I. | Mounted. Dr. Geo. Suckley. 
tains, St. Mary’s. ? Stevens. 
PEROGNATHUS FLAVUS, Baird. 
Perognathus flavus, Bairp, Pr. A. N. Sc. Phila. VII, April, 1855, 332. 
Sp. Cu.—Considerably 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 
