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 Algce 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, moUusks, 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, Sec, which take them greedily, their capture being 

 distinguished in Provence under the name of Pesquo a 

 la baboue, the latter being the name applied to these ani- 

 mals as well as the parasitical Cymothoce. This is done 

 by tying together bundles of Fucus ericoides, which are 

 sunk into the sea, and quickly adopted by the Idotece as 

 new places of retreat, and which at certain intervals are 

 drawn up, and the Idotece, as well as great numbers of 

 Talitrus, called Mourpuros, Sphcerumce, and other Isopods, 

 shaken out. 



