Descriptions of East Asiatic Mammals 299 
tiny kangaroos; they accomplish prodigious leaps with their 
powerful hind legs. 
the striped mice and jumping mice 
(family zapodid^:) 
The Zapodidae include but two genera, Zapus and Sicista. 
These genera are so different from one another that they are 
often placed in separate subfamilies. Members of the genus 
Zapus have grooved upper incisor teeth, with the grooves, easily 
seen, running up the face of each front tooth ; Sicista has the 
incisor teeth ungrooved. Both look more mouse-like than do 
the Jerboas. Sicista, which does not jump far, has shorter hind 
legs. 
The Birch Mice or Striped Mice, genus Sicista, have slen- 
der but not especially long hind limbs and the tail considerably 
longer than the head and body. All the species that occur in 
Asia seem to be rare. They extend from Kashmir through cen- 
tral China to Mongolia. The typical species, S. subtilis, ranges 
from Russia eastward. Other species are found east and south- 
east of Russia but only three, two northern forms and a Hima- 
layan species, reach the eastern Asiatic areas under present con- 
sideration. 
The Concolorous Birch Mouse, Sicista concolor, originally 
from Kansu, was found also near Kirin by Sowerby. It is col- 
ored rather uniformly brown, the sides paler and more reddish, 
the underparts pale brown. The ears are brown, the feet white. 
The length of the head and body is 2% inches, tail 4*4 inches, 
hind foot % inch. 
The Long-tailed Birch Mouse, 5*. concolor caudata, is a 
relative from Sakhalin. It is smaller and lacks the dorsal stripe 
of 5*. subtilis. The length of the head and body is 2% inches, tail 
4% inches, hind foot % inch. 
The Yellow Birch Mouse, S. flavus, is from Kashmir. It is 
mentioned here because its range may possibly extend east of the 
