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, Lai .,) have 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 . By'ogn., 
"*V 
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, 
