148 University of California Publications in Zoology. (Vou. 5 
leneth than the males. Doubtless many of the latter have suf- 
fered so slight caudal amputations as to have been ineluded in 
the measured list unnoticed. The males alone appear to be 
subject to such mutilations (which are probably incurred during 
fights) as not a single female unquestionably so marked was ob- 
tained. As compared with a series of N. f. macrotis from the 
Pacific slope of Los Angeles county, mohavensis is very much 
paler, the rump redder, the tail more distinctly bi-color, the dorsal 
surface of the hind feet usually pure white (25 per cent. of adults 
have partial dusky cloudings). Several females taken along the 
upper Santa Ana in June and July had a distinet sulphur yellow 
tinge to the lower surface; but this has entirely faded out during 
the two years since those specimens were obtained. 
Microtus californicus californicus (Peale). 
California Meadow Mouse. 
This was an abundant mammal in many of the Transition 
zone Gienagas, especially those around Bluff lake. The majority 
of our specimens were trapped in that vicinity in the latter half 
of July, and the last of August and first of September, 1905. 
Their runways through the short grass and beneath the rank 
Veratrum herbage and willow thickets were numerous; our traps 
baited with rolled oats brought plentiful returns as far as this 
species was concerned. Strangely enough the majority of our 
specimens were captured in the daytime, showing that here, at 
least, the species does most of its foraging by daylight. Some 
of those so taken were youngsters, not over one-fourth grown, 
their fur yet very short. 
We did not find meadow mice over towards the desert; but 
along the upper Santa Ana they were fairly common. A cienaga 
at 6700 feet altitude on the south base of Sugarloaf showed plen- 
tiful signs of them. 
Microtus mordax bernardinus Merriam. 
San Bernardino Meadow Mouse. 
This species we found only in the highest and coldest 
meadows; in other words, those of the Boreal zone. I trapped 
