52 VETERINARY PARASITOLOGY 
2. HELMINTHES. 
These are divided into : 
1. Platyhelminthes, or Platodes (flat-worms). 
2. Nemathelminthes, or Nematodes (round-wormis). 
The former are practically all hermaphrodite. 
They are again divided into two classes : 
(x) Cestodes. 
(2) Trematodes. 
(1) The Cestodes contain the tapeworms. They have 
long, flattened, ribbon-like bodies, distinctly segmented, 
and a head provided in most cases with hooks and suckers. 
The Tenioide are the most highly developed. 
The Bothriocephalide are allied. 
In the Tznioide in general the head bears from two 
to four suckers. Between these, and centrally placed, 
there may be a rostellum, armed with one or more circles 
of hooks or spines, or in some cases there is merely a 
depression provided with a pore. 
The body tapers anteriorly, and the segments gradu- 
ally become ripe from behind forwards; hence the ter- 
minal segments are usually crammed with eggs. The 
segments multiply by a process of division from behind 
the head at the same rate as the terminal segments are 
shed or have withered, as the case may be. Each seg- 
ment is hermaphrodite, and provided with one or two 
genital pores opening out from a uterus, usually con- 
sisting of a median trunk and numerous lateral branches. 
The position of the genital pores varies. Thus, in 
Tenia cucumerina there is one on either side of each 
segment, while in Tenia marginata they are arranged on 
opposite sides, one in each segment. In Tenia litterata, 
again, the genital pores are centrally placed. 
In all the Tenioide the embryo escapes from the 
ovum and enters the alimentary tract armed with six 
