44 Description of a New Species of Dipodomys. [Jan. 
miles from where it leaves the mountains, but succeeded in 
finding no more colonies, though several miners whom I met 
knew the animal, and thought they were not rare. From the 
colony found in June I obtained three D. phillipsi and three more 
of the new species, which I have named Dipodomys deserti. As 
the river was now dry in this part of its course, I was able to 
spend but two nights at the place. The colony appeared to be 
nearly deserted, but I do not think I obtained them all. I 
brought two animals of each species home alive, and still have 
them in captivity. On my way home I camped one night in the 
Cajon Pass, at an altitude of about three thousand five hundred 
feet. The night was very cold for this region, ice forming in my 
canteen and coffee-pot. The D. deserti suffered badly. I had 
not expected so severe a night, and had given them no protec- 
tion more than to turn the open side of the box (which was cov- 
ered with wire netting) to another box. At sunrise I noticed 
that one of the D. deserti seemed uneasy, and a closer inspec- 
tion showed that its tail was frozen as stiffasastick. In turning 
about in its narrow quarters it had broken off about two inches 
of the tail, the piece lying on the floor. The other D. deserti 
had not suffered so much, but it ultimately lost most of the ter- 
minal white tuft. The D. phillipsi seemed none the worse for the 
frost, and probably are a hardier race, which may account for 
their wider distribution. 
The following notes on habits are based mainly on observa- 
tions of my captives. The D. deserti especially have become 
_very interesting pets, and allow handling freely. I often turn 
em loose in a room of my house, usually but one at a time, as 
they are somewhat quarrelsome, especially the one with the 
frosted tail, the accident having made it somewhat bad-tempered. 
It is quite pugnacious, driving the others about so that they 
often return to their cages. The D. phillipsi do not pay much 
attention to the peaceable D. deserti, but when the other comes 
near they promptly leap away. When the two species were 
first turned loose together they had an all-round fight, but the riot 
did not last long, the heavier D. deserti being easily victorious. 
The actions of both species in fighting are much alike. When 
both are disposed to stand their ground they stand nearly erect, 
facing one another, and apparently cuff and scratch with the 
fore feet, the motions being too quick to follow accurately with 
