Descriptions of East Asiatic Mammals 31 
It is probably true that all of the Insectivora actually eat 
insects and to that extent merit their name. But the name is not 
exclusive; the habit of eating insects turns up in many other 
orders. In mammalogy, the order of insectivores signifies not a 
type of behavior but a certain group of interrelated mammals. 
THE TREE-SHREWS (FAMILY TUPAIID^) 
Although the Tree-shrews are so much like small squirrels in 
external appearance, the long, slender snout will show their dis- 
tinctness from all of those except the long-nosed squirrels of 
southern Asia. Their numerous sharp front teeth distinguish 
them from the squirrels, which have paired upper and lower 
gnawing teeth like other rodents. In most of the species the tail 
is hairy, with most of the hairs growing out from the sides. The 
animals are active tree-climbers during the day. 
Two subfamilies are recognized: the True Tree-shrews, 
Tupaiinse, and the Pen-tailed Tree-shrews, Ptilocercinse. The 
former is composed of several genera; the later of one genus 
only, Ptilocercus. 
The Pen-tailed Tree-shrew, Ptilocercus, may be at once 
distinguished from other Tree-shrews by the fact that its tail 
bears a large terminal tuft of hairs arranged distichously, or like 
the webs of a bird's feather. The ears also are large and mem- 
branous instead of small and cartilaginous. The color of the fur 
is pale brown, with shades of drab and gray. A black mark runs 
through each eye. The body color extends nearly to the base of 
the tail, beyond which it changes ; the basal part of the " feather'' is 
black and the end part white or cream. The length of the head and 
body is from 5 to 6 inches, tail 6V2 to 6% inches, hind foot 1% 
inches. The only known species is P. lowi, with a race continen- 
tis. The original P. lowi lives on the island of Borneo; the 
mainland race is known from the lower half of the Malay 
Peninsula. 
