348 CLASS CRUSTACEA. 



two in number, and sometimes pedunculated ; several of them 

 have, besides, a simple eye. 



These animals represent, in the class of the Crustacea, the 

 myriapoda of that of the insects. 



These Crustacea are distinguished into two principal 

 groups. 



The one, (Ceratophthalma, Laf. ,)ha.ve ten pair of feet, 

 at the least, and twenty-two, at most, without a vesicular body 

 at their basis^ and the anterior of which are never longer than 

 the others, nor ramified ; their body is either enclosed in a 

 testa, in form of a bivalve shell, or naked, with each of the 

 thoracic divisions supporting a pair of feet uncovered ; the 

 eyes are sometimes sessile, small, and very much approxi- 

 mated ; sometimes, and most frequently, they are situated at 

 the extremity of two mobile pedicles. The eggs are either 

 interior or exterior, and enclosed in a capsule at the base of 

 the tail. 



Here the eyes are sessile, immoveable, and the body is 

 enclosed in an oval testa, having the form of a bivalve shell. 

 The ovaries are always internal. Such are 



LiMNADiA, Adolph. Brogn., 



Which are so closely connected with the preceding, that the 

 only known species has been placed among the daphnia by 

 the younger Hermann. The testa is bivalve, oval, and en- 

 closes the body, which is linear, and inflected in front. At 

 the head, and almost confounded with it, are, first, two eyes 

 placed transversely, and very closely approximated ; secondly, 

 four antennae, two of which are much the largest, each com- 

 posed of a peduncle of eight articulations, and of two 

 branches or filaments, setaceous, divided into eight articula- 

 tions, and a little silky; the other two intermediate ones, are 

 small, simple, and broad at their extremity ; thirdly, the mouth, 



