378 IDOTEA. 
animal by the existence of five pairs of very delicate 
branchial appendages (each appendage bears two plates), 
and a strong outer pair (which are the terminal uropoda), 
forming an operculum, opening laterally and shutting 
over the branchial apparatus. 
M. Polydore Roux, in his fine work on the Crustacea 
of the Mediterranean, gives some interesting details of 
the habits of these animals, which abound in places where 
the sea has brought together masses of Alge in a state of 
decomposition; here, at the depth of a foot or two in 
tranquil water, they multiply rapidly, feeding voraciously 
on dead fishes, mollusks, annelids, and other animal 
matters, gnawing also the meshes of nets of fishermen. 
They are essentially nocturnal, avoiding the light of day 
by hiding themselves under marine plants, but never 
under stones, and coming forth to feed after dark, some- 
times in such vast numbers as, in company with small 
Paguri, shrimps, &c., to consume a large amount of 
the fish caught in nets. They crawl with facility at the 
bottom of the sea, and swim easily by agitating the 
plates of the tail, When the sea is rough, they seek 
deep water, and are often thrown back by the action of 
the waves. They are much used by fishermen in the 
Mediterranean as baits for different species of Psarus, 
Perca, &c., which take them greedily, their capture being 
distinguished in Provence under the name of Pesqguo a 
la baboué, the latter being the name applied to these ani- 
mals as well as the parasitical Cymothoe. ‘This is done 
by tying together bundles of Fucus ericoides, which are 
sunk into the sea, and quickly adopted by the Idotee as 
new places of retreat, and which at certain intervals are 
drawn up, and the Idotee, as well as great numbers of 
Talitrus, called Mourpuros, Spheroma, and other Isopods, 
shaken out. 
