ORDER PCECILOPODA. 
371 
vi. 2; Monoculus gyrini, Cuv. Tab. Elem. cle l’Hist. Nat des 
An. p. 454; Ozolus gasierostei , Lat. ; Hist. Nat. des Crust, 
et des Insect. IV. xxix. 1 — -7 ; Desm. Consid. L. i. ; Pou da 
gasteroste, Baker, Micros. II. xxiv.) fixes itself on the under 
part of the body of the tadpoles of frogs, of stickle-backs, &c., 
and sucks their blood. Its body is flatted, of a clear yellowish 
green, and about two lines and a half in length. The younger 
Hermann, who has very well described this animal in its per- 
fect state, and who quotes a manuscript of Leonard Baldaneur, 
a fisherman of Strasburg, bearing the date of 1666, in which 
the same animal is figured, says, that it is seldom to be met 
with in the environs of that city, except on trouts, and that it 
often causes their death, especially of those which are kept in 
fish-ponds. It is also found on perch, pikes, and carps. It has 
never been found upon the gills. Like the gyrini, this animal 
whirls round like a top. He says that its body is divided into 
five rings, not very distinct, upon the back. 
Caligus, Mull., 
Have no cupper-feet ; those of the anterior pairs are un- 
guiculated, the others are divided into a number, more or 
less considerable, of pinuulse, or in the form of membranaceous 
leaflets. The testa leaves discovered a good part of the body, 
which is terminated posteriorly, in the majority, by two long 
filaments, and in the others by appendages, in the form of a 
fin or stylet. This interval also frequently presents some 
other appendages, but small, or much less projecting. 
The name of Jish-lice , under which they are collectively 
designated, indicates that their habits are the same as those 
of the arguli, and the other siphonostomata. Many naturalists 
have considered the tubular filaments of the posterior extre- 
mity of their body to be ovaries. I have sometimes discovered 
eggs under the posterior and branchial feet; but never in 
these tubes. Moreover, we never see any exterior oviducts, 
B b 2 
