RODENTIA—SACCOMYINAE——PEROGNATHUS PENICILLATUS. 419 
tail is considerably longer than the body, thick at base and tapering gently to the tip; it is 
everywhere covered densely with stiff appressed hairs ; those on the upper side commencing to 
elongate at about the middle, and soon attain a length of half an inch, standing up obliquely, 
like a crest, towards the end of the tail, which is terminated by a condensed brush. The feet 
are rather large; the nail on the rudimentary thumb very small; the third claw longest; the 
first a little shorter ; the second reaching to the middle of the third; the fifth to the middle of 
the second ; the claws of the hand are considerably larger than on the foot. The short first toe 
reaches to the base of the second toe; the third toe is longest; the second and fourth equal and 
a little shorter ; the end of the fifth claw extends as far as the antepenultimate joint ot the 
fourth toe. The soles are entirely naked from the heel, with a few scattered hairs along the 
sides, and covered with a pavement of depressed scale-like tubercles. 
The upper parts generally are of a dull light yellowish brown or tawney, lined with dark brown, 
paler on the sides. The hairs have a lustrous tint of fresh cut lead for about two-thirds from 
the base, becoming a little darker outwards; they then assume the dull yellowish brown as 
described, and a considerable number are finally tipped with dark brown. Beneath, and on the 
lower part of the sides, the entire fore leg and the hind foot are dirty white. The line of sepa- 
ration on the sides passes nearly straight along the sides from the cheeks. The ears are dusky, 
without an appreciably lighter margin. The tail is dull white below, to within about half an 
inch of the end of the vertebre ; from which point, with the entire upper side to the tip, it is 
dark hair-brown. 
This species is readily distinguished from P. monticola by its larger size; larger and more 
naked ears; much longer and penicillated tail; larger feet; shorter pouch openings; lighter 
color, and the color of the back not dipping down on the arm at all, instead of extending in a 
lighter shade to the wrist. It is without the yellow lateral stripe of P. fasciatus. It is not im- 
probable that the specimen caught on King’s River, California, by Dr. Heermann, and referred 
by me to P. parvus, of Peale, may prove to be a very young specimen of this species, as they 
agree in the large feet, &e. Perognathus flavus is distinguished by the brighter color, shorter 
feet and tail, which is not penicillated, and other characters. 
The preceding description was taken from Dr. Woodhouse’s specimen. Since then several 
specimens collected on the Colorado have been received, all agreeing remarkably in characters 
with the first mentioned. The colors of the under parts are better defined, however, the white 
of the cheeks extending a short distance below the eye, and involving the entire side and 
extreme tip of the muzzle. The extreme tip of the tail all round is plumbeous. 
List of specimens. 
Measurements. 
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2676 | San Francisco Mts., | 1851....... Capt. L. Sitgreaves...|....| Mounted.|..../ .92)..../4.12/4,50/5.08! .40) .96! .13} .12] .30) Dr. S. W. Wood- 
N. M. house. 
1332 | Colorado river, Cal...) Peb.22,1855| Maj. W. H. Emory...| 5 | Skin..... veeelecee| ccee(d.4013, 0013.62) eee] -Dlisceeleecelecee A. Schott.....005 
1333 | Near Fort Yuma, Cal.|....00cccscsleceseees dO. . sevecccce. B frnccdO.e cc] sccolecee|oecel4.20/9.00/4,15] 39] .I5}sanslevse| sD0/coccesOns cesscces 
1349 | Colorado desert, Cal.|...cesseecesleceeeees GO. ssecceceeslecee| Inale...| 50) .90/1.00/2.50/3,15}....] .34 tT) eseeleces[eeeeleeeeesdOrs eee eeee 
