66 STEPPE FAUNAS AND TEMPERATE 
burrows in companies. With the vegetable food they 
mingle insects and the eggs and young of birds, 
especially of the steppe lark. 
The jerboas of the genus Dipus chiefly inhabit the 
hot deserts further south, but some species, notably 
D. sagitta, extend into the steppes. Though the habits 
of the members of this genus are generally similar to 
those of the preceding in their coloration and in their 
intolerance of rain or damp, they are essentially in- 
habitants of arid regions (cf. p. 133). 
In the steppe region are also found the hamsters 
(Cricetus), with a western extension into Europe. But 
though originally doubtless steppe animals, the ham- 
sters, like the brown and black rats, though to a less 
extent, have attached themselves to man, and find it 
more profitable to plunder his fields and gardens, than 
to depend upon the precarious vegetation of the steppes. 
They are remarkable for the size and elaboration of 
their burrows, in which they store quantities of corn, 
&c., for winter use. 
Another characteristic genus of the steppe is Lagomys, 
the genus which includes the picas, tailless hares or 
whistling hares as they are variously called. These 
animals are smaller than a rabbit, and are for the most 
part mountain animals, living high up among rocks 
and stones in the mountains of Central Asia. In Siberia, 
however, they are found on lower ground, and even 
extend into the tundra region. They form a very 
important part of the food of the carnivores of the high 
steppe, replacing here the lemming of the tundra. In 
Mongolia, Z. ogotona occurs in large colonies, and at 
the approach of winter stores up large quantities of 
hay near the openings of the holes. According to 
Prejevalski, these haystacks may weigh 10 kilogrammes 
