New Species of Field Mouse. 703 
on the north side. The hills where I have found them are all 
steepest on the north side, which may have some effect, though 
there seems to be no difference in the vegetation on different 
sides. Like other Arvicole, they have many holes, and prob- 
ably live in families or colonies, although I have not caught more 
than one at a group of holes; but from the difficulty in catehing 
them this does not signify anything (have caught only four). 
“Where there is grass or weeds, their holes are connected by 
beaten paths in the same manner as those of Arvicola austerus, but 
in many places they are in bare clay. Their food seems to consist 
largely of the flowers of certain plants, judging from the remains of 
flowers scattered around the holes, and from the contents of their 
stomachs and excrement. When these plants grow near, there are 
usually pieces of stems and blossoms of Liatris graminifolia adn 
Artemisia frigida lying about, but many other plants and grasses 
seem to be eaten. They feed largely on the seeds of Eurotia lanata. 
I found a place near their holes where something had dug down to 
a partly-eaten bulb of Liatris graminifolia. Probably these bulbs 
form a part of their diet, as is the case with Arvicola austerus. I 
placed corn, oats, cactus seeds, and seeds of weeds around their 
holes, but they remained untouched. The same was true of bread 
and cheese, and fried cake was seldom eaten. They seem suspicious 
of traps, and evidently leave their holes when traps are set near 
them. I have caught several grasshopper mice (Onychomys leuco- 
gaster) and Western white-footed mice (Hesperomys leucopus sonori- 
ensis) at their holes, and think these species either drive out the 
Arvicolw or else inhabit the old holes.” The exact locality where 
these specimens were obtained, writes. Mr. Bailey, “is not actually 
in the extreme ‘ bad lands,’ but near the edge, where the land is 
about ‘half bad.’ From the fact that they live entirely in the hills 
and usually near the tops, where it is very dry, it might be inferred 
that their true home is in the ‘bad lands?” 
In comparing these mice with the other known North Ameri- 
“an species of Arvicola, two. striking external differences are 
observed, namely, (1) extreme paleness in coloration ; (2) extreme 
shortness of tail. The color is paler even than that of the Muskee- 
get d mouse (Arvicola breweri), and the tail is shorter than 
that of any other species, not excepting A. pinetorum, in this respect 
agreeing closely with Synaptomys cooperi. The ears are unusually 
