Cestoidea.- 
-ENTOZOA.- 
-Entozoa. 
increase in size, and at the end of eight weeks it was 
found to have grown from the size of a pea to the length 
of from thirty-six to 
thirty-nine inches. 
The most generally 
known and perhaps the 
largest of all the Tape- 
worms, is the species 
which inhabits the in- 
testinal canal of man. 
Fig. 208 is that of the 
Tatnia crasfiicollis men- 
tioned above. 
The Cystic worms, 
formerly constituting a 
separate order, Cestoi- 
dea, and now provi- 
sionally a family, Cysti- 
cidce, are only, as 
mentioned above, stray 
Toenice, which have 
assumed a vesicular 
form and have not 
developed genital or- 
gans. They are the 
produce of the micro- 
scopic ova of the Ces- 
toid worms belonging 
to certain carnivorous 
animals accidentally 
introduced into the 
bodies of rodent or 
ruminant quadrupeds. 
In such situations these 
ova are not 
worms, hut 
Fig. 208.— Tsenia crassicollis. 
developed into elongated, articulated Tape- 
into Cystoid worms, the body being termi- 
nated by a vesicle of a 
bottle-shape and filled 
with fluid. They do 
not assume their per- 
fect form till they 
have passed through 
the stomach of the 
Carnivora to which they 
originallybelonged; but 
nevertheless while in 
their undeveloped form 
as Cj'stoid worms, they 
produce intense suffer- 
ing, serious illness, and 
ultimately death, in the 
poor creatures in whose 
bodies they have taken 
up their abode. Such 
are the species of Cysti- 
cei'cus, Cosnuriis, &c. 
The history of the 
worms called Entozoa 
is full of interest, but 
in a work of this sort 
we must content our- 
selves with merely a 
brief sketch of the clas- 
sification and leading 
families and genera. 
Enough, we trust, has 
been said to stimulate 
inquiry, and to aid the 
reader in pursuing it. 
END OF CRUSTACEA, ETC. 
