338 
CLASS CRUSTACEA. 
culi of Jurine, his second family. The form of two of their 
antennae, which resemble two ramified arms, serving as oars, 
and the faculty which they have of jumping, have caused 
one of their most common species to be called the arbo- 
rescent aquatic flea. 
The first of these naturalists, who has given us an excellent 
monograph of Daphnia, a subgenus of this division, has esta- 
blished two new ones, one under the denomination of La- 
tona, having as character, the antennae in the form of oars, 
divided into three branches, and of a siugle articulation; 
( Daphnia Setifera, Mull.) and the other that of Sid A, approxi- 
mating to the known subgenera of the same division, with 
relation to the same antennae, divided only into two branches, 
but one of which has two articulations, and the other three. 
(. Daphnia cristallina, Mull.) According to him, the daphnia 
should be distinguished from the preceding, and from the 
lyncea;, by one of the two branches of the oars being composed 
of three articulations, and the other of four. Nevertheless, 
Jurine (Hist, des Mon. p. 92.) says, that each branch is com- 
posed of three articulations ; but it appears that he took no 
account of the first of the posterior branch, which is indeed 
very short. The last in all those lophyropa, is terminated by 
three filaments, and each of the preceding gives out another. 
These filaments are simple or barbed. There exist also two 
other antennae, but very short, especially in the females, 
situated at the anterior and inferior extremity of the head, 
and which have hut a single articulation, with one or two 
setae at the end. 
Polyphemus, Mull., 
Have, as well as daphnia and lynceus, their antennae in the 
form of oars, divided into two branches ; but each of them is 
composed of five articulations. Moreover, their head, very 
distinct, and rounded, supported on a sort of neck, is almost 
