56 VETERINARY PARASITOLOGY 
(5) Strongylide.—In these the body is rounded, and 
but seldom thread-like. The mouth bears six oval 
papille. The males have the vent enclosed in a divided 
or entire caudal pouch, from which the organ of genera- 
tion can be protruded. There are usually one or two 
“claspers.”’ 
The three chief groups of the Strongyles are : 
(a2) The Eustrongylines. 
(2) The Strongylines. 
(c) The Sclerostomines. 
The chief differences are set out in the following 
table : 
Mouth. Caudal Pouch. 
Eustrongylines .. Non-chitinous Not ribbed 
Strongylines a Non-chitinous Ribbed 
Sclerostomines .. Chitinous Ribbed 
2. THE ACANTHOCEPHALA. 
These worms are provided with a sort of proboscis, set 
with recurved spines, by means of which they attach 
themselves to the intestinal mucous membrane. 
Echinorhyncus gigas of the pig is the largest known 
member. 
Digestive organs are absent, with the exception of 
two small blind tubes arising at the base of the pro- 
boscis. 
The males probably fertilize the ova after they have 
been excluded. 
