RODENTIA—MURINAE—HESPEROMYS GAMBELII. 465 
Oolor.—Above, mixed glossy brown and yellowish brown, the former predominating on the 
back. Sides but little paler. Ears dusky. The white of the fore leg extending as far as the 
elbow. Under parts and feet white. Tail white, dusky above; the difference of color very 
evident. 
Several specimens of Hesperomys were caught at Posa Creek by Dr. Heermann, differing in 
some respects from the others brought in from the west by exploring parties. As they appear 
not quite grown, I hesitate about describing them as new, and, for the present, at least, prefer 
to place them under H. gambelit. 
This species differs from H. boylii in the much shorter tail and less number of caudal verte- 
bree, more villose ears, with longer fur at their inner base on the top of the head, shorter hind 
feet, &e. 
This species, in size and general appearance, represents very closely the Hesperomys leucopus of 
the eastern States to such a degree, in fact, that as yet I have not found any easily expressed 
characters to distinguish them. There is the same plumbeous hue in the young, the yellowish 
brown of the back, &c. Ido not find, however, a tendency to a distinct darker stripe on the 
middle of the back, as in H. leucopus, and the general appearance of a series of each is quite 
different. It is barely possible that my H. austerus may be a northern variety of the common 
Californian species, of smaller size and darker color, somewhat like the gray and smaller H. 
leucopus of Nova Scotia, and probably Labrador. The differences, however, are considerable, 
and further materials will be necessary to decide the question. 
List of specimens. 
= Measurements. 
x | Ss = 
z\s : 3 slelelelelals 
EI = Locality. When col- Whence and how | Nature of asl se = ta Nes 5 £ Si & Bs Collected by— 
ey alice lected. obtained. Z |specimen| >|S)/S ies jerlslcolelel/2iez 
& fo = calbonlie lioness leepieoe ite cans 
S a 5 ee | ee Wes Ge Wecinere [ied eet St lc 
gs |: ‘© 2)/8)el/e|sle)\PlBl Pisce 
6/8 6 zleiz|2/@|8/3)8)a/ 5 |e | 
663 |1844) Nachess Pass, Cascade) July 1,1854 | Gov. I. I. Stevens..|....| Skin..... seee|eees|eeee|d.00/2,85/3.00 7 .65, Dr. J. G.Cooper. 
mountains, W. T. 
78101 /2012) Astoria, O. T.........|eeeee coos | Lit. Trowbridge o.00|s0c-|oeerDOr.ss|eccslevcs|aeve its 
?998 |2224) Fort Dalles, O. T..... Feb., 1855..| Dr. Geo. Suckley...} 42 |....d0....|s+0.Jee+ - 
1262 |....| Klamath lake, O.T.:.|.....0eeeees Lt. Williamson ....|....| Mounted.|....|..+.|.++ 
2561 |....| Petaluma, Cal... cecceccncees E. Samuels......e./eeee Inale...| . 
2562 |. -.do 
2563 |... ..do 
2564 |... «do 
2565 |. «do 
2566 |.... ceclec nego [Neen Grass 
2567 |....| Tomales bay, Cal..... woceescecnes ° weee|seeeGQ....) « 
RIGS |. onclecsescecDQsccccscccnec(eces coscser do. 
QSED |... Jerre cece AOnecceee ee aee00ce a. 
QTD JoccelecsevecedOs. savcccccelooes sees us| copy Oss 
284 |....| San Francisco, Cal,,.| Winter.... Sens} SEAMS. 555 sone] same) alefaiin 
368 |1282) Monterey, Cal........|/.sceeseveees Lt. Trowbridge....|....| Mounted.|....|... |.... 
369 |1283)........d0...... eesvcelece bwccclecs| veer secs do..... + encelecce|seecDQre. 
A76 1601) Posa creek, Cal. . 5 | .00sd0s... Jove eee 
ATT | ccccleeccces ADrscccrcnvces|scccccsccccs:|sececces dO. seccces 4 | oneedO.e.Jocee|.cocleoes ae wad |boee 
478 1002 |-aeereeedOe wesevsrreeleoreeeeveens secceser GOs secccece 7 |nsetGOs.s0loves vewe|een|daes|ccce|aans 
1 Possibly H. boylii. 
59 L 
