CRUSTACEA. 
215 
of which, very large and more or less oval, forms the head, and the 
posterior, corresponding to the thorax, transverse and angular in its 
circumference, supports the foot-jaws and feet. These latter, with 
the exception at most of the two posterior and two last foot-jaws, are 
slender and filiform, usually veiy long and accompanied by a lateral, 
ciliated appendage. The other four foot-jaws are very small and 
conical. The base of the lateral antennae exhibits no scale ; the 
intermediaries are terminated by two threads. The ocular pedicles 
are long. The body is much flattened, membranous, and diaphanous ; 
the abdomen small and its posterior fin without spines. It comprises 
but a single genus, the 
Phyllosoma, Leachy 
Of which all the species inhabit the Atlantic Ocean and Oriental 
seas *. 
MALACOSTRACA. 
h. Eyes sessile and immoveable. 
The Branchiopoda are the only Crustacea of which we shall hence- 
forward have occasion to speak, that exhibit eyes jdaced on pedicles. 
But independently of the fact that these pedicles are neither articu- 
lated nor lodged in special cavities, the Branchiopoda have no shell, 
and are otherwise removed from the preceding Crustacea by various 
characters. All the Malacostraca of this division are also deprived 
of a shell; their body, from the head downwards, is composed of a 
suite of articulations of which each of the first seven is furnished 
with a pair of feet, the following and last ones, seven at most, form- 
ing a sort of tail terminated by fins or styliform appendages. The 
head presents four antennee, the two intermediate superior, two eyes, 
and a mouth composed of two mandibles, a tongue, two pairs of jaws, 
and a sort of lip formed by two foot-jaws that correspond to the two 
superior ones of the Decapoda ; here, as in the Stomapoda, the 
flagruin no longer exists. The four last foot-jaws are transformed 
* See Encyclop. Method., and Nouv. Diet. Hist. Nat., Ed. 11, article Ph\jl~ 
losome ; also the work of Desmarest on. the Crustaeea and the Zoology of the Voy. 
de Freyciuet. As respects their nervous system, the Phyllosoma; seem to be in- 
termediate between the preceding and subsequent Crustacea. See Audouin and 
Edwards, op. cit. 
