38 ANIMAL COMPETITORS 
ears, half an inch long, very small eyes, and 
long naked tail, are unlike those of any native 
mouse. Its total length is about 7 inches, 314 
of which belong to the tail. Its molar teeth 
have each three tubercles, instead of two, as 
in our own wood-mice; and its incisors are un- 
grooved, by which, at any rate with the aid of 
a magnifying glass, the marks of its biting are 
readily identified. 
Its gray protective coat has seemed satis- 
factory under all circumstances, for there is no 
perceptible difference between representatives 
of the species in the four quarters of the globe. 
In general the type seems singularly invariable, 
only one or two varieties having arisen, such as 
the queer rhinoceros mice which appeared in 
England some years ago, and took their name 
from their hairless, deeply-folded skin which 
gave them the appearance of miniature rhinos. 
This fixity of type may be due in part to the 
fact that every country has received a con- 
stant immigration of fresh blood by means of 
ships and other conveyances. 
Japanese dancing-mice. One strange vari- 
ety, however, has arisen, probably in China 
