ORDER BRANCHIOPODA. 
325 
Fabricius, and of Linnaeus, was composed, with the omission 
of a single species (M. Polyphemus ), only of the genus 
Monoculus, Linn. % 
Which we shall divide into two principal sections. 
The first, that of Lophyropa, is distinguished by the num- 
ber of the feet, which never exceeds ten. Their articulations, 
besides, are more or less cylindrical or conical, and never 
entirely lamelliform or foliaceous. Their gills are not nu- 
merous, and the majority of these animals have but a single 
eye. Several, moreover, have mandibles furnished with a 
palpus. M. Straus, indeed, appears to attribute this character 
exclusively to cypris and cytherea , which compose his order 
of ostrapoda; but the observations of the elder Jurine, and of 
M. Ramdohr, prove that it is also proper to the Cyclopes . The 
antennae are almost always four in number, and serve for the 
purpose of locomotion. 
In the second section, that of Phyllopa, the number of 
the feet is twenty at least, and in some, much more consider- 
able. Their articulations, or at least the last ones, are flatted, 
in the form of ciliated leaflets. Their mandibles never ex- 
hibit palpi. They all have two eyes, situated in some at the 
extremity of two movable pedicles. Their antennae, the 
number of which, in several, is but two, are generally small, 
■and not adapted for swimming. 
We shall divide the Lopijyropa into three principal 
groups, very natural, and the first two of which approximate 
to the Crustacea of the first three orders, in consequence of 
their mandibles having each one palpus, and likewise from 
some other characters. 
1st. Those (Carcinoida, Lat.) whose testa, more or less 
ovoid, or ovaliform, is not bent in two like a bivalve shell, 
* In the system of Geoffroy, the genus Binoculus is included. 
