38 PARASITOLOGY. 
HEMATOPINUS PILIFERUS (Pilus—a hair). 
Animal Intested.—This is the blood-sucking louse 
of the dog. 
Description.—Its head is short, almost as long as 
broad. The antennae and legs are short and the 
abdomen is large and oval in shape. 
HEMATOPINUS STENOPSIS (Stenos—narrow). 
Animals Infested.—Goats and sheep. 
Description.—The head is long and narrow; thorax 
short; abdomen long. 
TRICHODECTES (Trix—a hair; dectos—biter). 
The species of this genus are small and light in 
color. The mouth parts are located on the under 
side of the head. The mandibles are strong and are 
arranged for mastication. The head is provided 
vith two simple eyes and two short antennae. The 
head is as wide as long, and wider than the thorax. 
The abdomen is globular in shape and divided into 
nine segments. Its food consists principally of epi- 
dermis. 
TRICHODECTES PiLosus (Pilos—a hair). 
Animals Infested.—The horse, the ass and the 
mule. 
Description.—The head is rounded in front; the 
antennae are inserted well back and are composed 
of three articles each. The abdomen is oval and 
tapers posteriorly. 
TRICHODECTES SCALARIS (Scalaris—to climb—a ladder). 
Animals Intested.—Cattle. 
Description.—This species is very common. Its 
