1910] Taylor.—Two New Rodents from Nevada. 291 
light brownish, or light fawn color, as in desertorwm from the 
Mohave Desert. But on the whole the Nevada skins are mark- 
edly different in this respect. Of twenty adults of the Mohave 
Desert species, mostly males, only one (no. 6087) approaches 
‘the Nevada series in color of tail dorsally. As a matter of fact, 
the color in this specimen is not the charcoal black of nevadensis, 
but seal brown. 
Differences between the two species are quite as evident in 
the juvenals as in the adults. Three young specimens of neva- 
densis (nos. 7886, 7885, 7889) taken in June and July and four 
of desertorum (nos. 53886, 5287, 53438, 5385) taken in June are 
at hand. ‘Two selected individuals (nos. 7886 and 5385) are 
of about the same age, and are typical of the two series of 
juvenals. As exemplified by these two specimens, nevadensis is 
darker than desertorum. The baek of the former is slate black 
with a few buffy hairs showing through. The latter has the 
dorsal surface hair brown. The face and forehead of nevadensis 
are dark gray with merely a suggestion of buffy, while deser- 
torum has these parts almost wholly buffy. Nevadensis has 
merely a suggestion of buff on the flanks and rump, while deser- 
torum has the color intensified. All of the youne specimens of 
the former present a buffy tinge on the white-tipped hairs of 
the ventral surface, while a number of examples of the young 
of the latter have the underparts pure white. There is great 
variation in both species in this respect. In the juvenals of 
nevadensis the region behind the ears is noticeably buffy, whereas 
in desertorum, although it is almost identical in tone, this mark- 
ing is not evident, since its color is much the same as that of 
the upper parts in general. In respect to coloration of the tail, 
the differences between the young of the two species are analo- 
gous to those between the adults. 
The table of comparative external measurements shows that 
the new form is uniformly smaller than desertorwm, except that 
the average of the hind foot for the females of nevadensis is 
slightly greater than that for the females of desertorwm. In 
other respects the difference in size is quite marked. The longer 
tail of desertorum makes the ratio of the hind foot to the total 
leneth greater in nevadensis than in desertorwm, while of course 
