PARASITOLOGY. 193 
Canina is the biting louse (Trichodectes Latus) and 
the flea (Pulex Serraticeps). These insect parasites 
become infested while procuring food which is con- 
taminated; the minute embryo is liberated in the di- 
gestive tract, migrates to the abdominal cavity and 
there forms a cyst known as the cryptocystis tricho- 
dectis (if formed in the louse) or cryptocystis 
pulecidae (if formed inthe flea). The dog, by biting 
itself to relieve the irritation caused by these insects, 
gets them in its mouth; thus the larva, which consists 
of the scolex or head, and neck, after being liberated 
through digestion finds its way to the small intes- 
tines, and attaching itself to the mucous membrane 
becomes fully developed in about five weeks. 
Animals Infested.—The adult infests the dog; 
the larval or cystic form infests the flea and louse of 
the dog. 
Symptoms.— Treatment.—Same as in the preceding 
species. ; 
Prophylaxvis.—Keep dogs and kennels free fro 
fleas and lice; in this way the chain of the life cycle 
is broken. 
TAPEWORMS OF THE CAT. 
The tapeworms of the cat are armed; the following 
is the most common. 
TAENIA CRASSICOLLIS. 
Distribution.—Found in the United States. . 
Description.—The worm may reach the length of 
five feet; the terminal segments are longer than wide; 
the head is provided with four sucker discs and a 
rostellum of from thirty to fifty hooklets ; the neck 
is thick and short. 
