368 ENTOZOA,. 
DEROSTOMA. 
Where the oral orifice is underneath but nearer to the anterior ex- 
tremity. 
It is to the first that I approximate the Paznicurus, Rud., or 
Vertumnus, Otto, in which there is but one orifice at the anterior 
extremity. 
But one species is known—V. thethidicola, Otto. Ac. Nat. 
Cur., XI, part II,pl. xli, f. 2—a parasite of the Thethys fim- 
bria; it is marbled, and frequently has a forked tail so shaped 
by being torn(1). 
FAMILY III. 
TENIOIDEA. 
In our third family of parenchymatous Intestinal Worms, 
we place all those species in which the head is provided with 
two or four suckers placed around its middle, which is itself 
sometimes marked with a pore, and sometimes furnished with 
a little proboscis, naked or armed with spines. Sometimes 
there are four little trunks thus armed. 
The most numerous genus is 
Tents, Lin. 
The body of the Zape-worm is often excessively elongated, flat, com- 
posed of joints more or less distinctly marked, and narrowed ante- 
riorly, where we generally find a square head hollowed by four small 
suckers. 
Observers have thought that they could perceive canals which 
= 
(1) For its anatomy, see Delle Chiaie, Memor., I, pl. ii, f. 9, 5. 
