352 CLASS CRUSTACEA. 



form of a beak, of which Schceffer speaks, and which M. Pre- 

 vost calls sucker, is not the labrum ; that the four bodies or 

 nipples, placed on the sides, and mentioned by the first, 

 are not the mandibles, and the two upper jaws; and that the 

 pieces considered by the second as barbies, are also not 

 maxillary. The first two feet which, according to Schceffer, 

 are composed but of two articulations, the last going into a 

 point, might represent the first two jaw-feet of the decapod 

 Crustacea, and the two large antenniform feet of apus. The 

 principal male sexual organs, or at least those which are re- 

 garded as such, consist of two conoid bodies, biarticulate, 

 and coming forth only on pressure, situated on the under part 

 of the second ring, at which some vessels end, that proceed 

 from the first. M. Prevost presumes that the two vulvse of 

 the female are at the extremity of the tail, but do not give 

 issue to the eggs. This issue (two apertures, according to 

 Schceffer,) is at the second ring, and communicates interiorly 

 with the sac enclosing the eggs, and serving as an external 

 matrix. But we are not acquainted with any crustaceous 

 animal in which the female sexual organs are placed at the 

 posterior extremity of the body, and therefore this opinion 

 appears to us to possess but slight foundation. 



The observations of Schceffer on the hairs of the feet of 

 these Crustacea demonstrate, that they are so many aerial 

 canals, and even the surface of the feet of which they are 

 composed, seems to absorb a portion of the air, which is 

 attached to it in the form of small bubbles. 



The Chirocephale diaphane of Benedict Prevost, and which 

 appears to us to have great relations with our hrancJiipe des 

 marais, if indeed it differ from it at all, has, on issuing from 

 the egg, the body divided into two masses, pretty nearly 

 equal, and almost globular. The first presents a simple eye, 

 two short antennae, two very large oars, ciliated at the end, 

 and two feet, rather short and slender, consisting of five arti- 



