298 CRUSTACEA. 



pressed and curved beneath posteriorly. The terminal appendages of the tail 

 are most frequently styliform and articulated. Most of them swim and leap 

 with facility and always laterally. Some inhabit springs and rivulets; most of 

 them however live in salt water. Their colour is uniform, verging on reddish 

 or greenish. 



They may all be comprised in a single genus, that of 



GAMMARUS, Fabricius. 



Which is now divided into various subgenera, such a&Phroninui, Hy/xria, &c. 

 Among the most interesting of these- is the 



COROPHIUM, Latreille. 



The C. longicornu, called Pemys, on the coast of Rochelle, lives in holes, 

 which it forms in the mud, that is covered with hurdles, called bouchots by the 

 inhabitants. The animal does not make its appearance till the beginning of 

 May. ft wages everlasting war against the Nereides, Amphinomae, Arenicolte, 

 and other marine Annulata, which inhabit the same locality. A curious spec- 

 t&cle is presented by these Crustacea when the tide is coming in ; myriads of 

 them may then be seen moving in every direction, beating the mud with their 

 great arms, and diluting it in order to discover their prey: is it one of the 

 above mentioned Annulata they have discovered, which is ten or twenty times 

 larger than themselves? they unite to attack and devour it. The carnage never 

 ceases until the mud has been thoroughly turned up and its inequalities levelled. 

 They do not even spare Mollusca, Fishes, or dead bodies on the shore. They 

 mount upon the hurdles which contain Muscles, and fishermen assert that they 

 will cut the threads that keep them there, in order to precipitate them into the 

 mud, where they may devour them at their leisure. 



ORDER IV. 



LjEMODIPODA.* 



THE Laemodipoda are the only Malacostraca with sessile eyes, in which the 

 posterior extremity of the body exhibits no distinct bran- 

 chiae, and which are almost deprived of a tail, the two last 

 feet being inserted in that extremity, or the segment which 

 connects them with it being merely followed by one or two 

 very small joints. They are also the only ones in which 

 the two anterior feet, that correspond to the second fjot- 

 jaws, form part of the head. 



They all have four setaceous antennae supported by a 

 triarticukted peduncle, mandibles without palpi, a vesicular body at the base 



Throat-footed. 



