PARASITES OF THE ALIMENTARY TRACT 55 
is a short tube, which can be slightly protruded. The 
male has no caudal pouch, but has two spicules, or 
“claspers.” The females have a straight digestive 
canal, and two tubular, spirally-arranged ovaries, several 
times longer than the body. They open at the vulva, 
which is situated at about one-fourth of the length from 
the anterior extremity. 
The Ascarides inhabit the small intestine, and may 
enter the stomach. The lumbricoid worms are found 
in the large intestine. 
(2) Oxyuride.—These worms inhabit the large intes- 
tine. They are oviparous. The mouth is provided 
with three lips, and the tail is tapered and much finer 
than the remainder of the body. The caudal pouch is 
absent in the male. 
(3) Filariide.—The body is long, slender, and thread- 
like, and the rings are less pronounced. The mouth is 
a circular opening. In females, the vulva is situated 
at the anterior end of the body. The males usually 
have the tail rolled up. They are not found in open 
cavities, but inhabit the parenchymatous tissues, being 
frequently embedded in the subcutaneous tissues (see 
Cutaneous Filariasis, p. 34), tendons, or within the an- 
terior chamber of the eye. These represent the Filaria 
type; but the Spiroptera embed themselves chiefly 
between the layers of the viscera, such as the cesophagus 
and stomach, in the form of nodules, under the mucous 
membrane. 
(4) Trichotrachelidze.—These are so called on account 
of the beaded or constricted cesophagus. The body 
is extremely slender, and tapers at the anterior 
extremity. 
There are two genera : 
(a) Tricocephalus, usually inhabiting the intestine. 
(0) Trichina, usually found encysted in muscular 
tissue. 
