480 CLASS ECHINODERMATA. 
in the brain of sheep, destroys a part of its substance, and 
occasions a sort of paralysis, called the staggers, because it 
causes them to turn round involuntarily as if they were giddy. 
Some of these worms have also been seen in oxen, and other 
ruminants, in which they produce the same effects. The 
vesicle is sometimes as big as an egg. Its parietes are very 
slender, fibrous, and exhibit sensible contractions. The small 
worms are scarcely half a line in length, and enter the vesicle 
by contraction. 
Here should, probably, come the genus, 
EcHINococcus, Rud., 
But I have not observed it, nor can I form a sufficiently dis- 
tinct notion of it, for the purposes of classification. 
ScoLex, Miill., 
Have the body round, pointed behind, very contractile, and 
terminated in front by a sort of variable head; round which 
are two or four suckers, sometimes in the form of ears, or 
small tongues. 
Only some very small ones are known, taken from some 
fish. 
I have seen a large one; Scol. gigas, Cuv., which pene- 
trates into the flesh of a species of bream, the sparus raz, L. 
the middle part of the body of which is inflated into a bladder, 
which in the living state contracts or enlarges alternately 
in its middle. It is the gymnorynchus reptans, Rud. Syn. 
129. 
The fourth family, 
CESTOIDES, 
Comprehends those in which no external suckers are ob- 
served. 
ee 
