228 
SUPPLEMENT 
As we have thus touched, however slightly, on the history 
of the classifications of Crustacea, it would be highly improper 
to pass over in silence the name of our distinguished country- 
man Dr. Leach. His labours on certain parts of this order 
are highly valuable, and at once excite our regret at their un- 
happy interruption, and our earnest hope of their auspicious 
recommencement and completion. The nature of our work 
will not permit us to follow all his details, or give a minute 
analysis of his distribution. His generic divisions are gene- 
rally noticed in our text, and nothing important in his re- 
searches shall be omitted in these supplementary additions. 
Although the name of Crustacea has become one of general 
usage, w’e may yet consider that of iiixilacostraca , as in some 
measure, if not altogether synonymous, although the latter has 
been used by M. Latreille and other recent writers, to indicate 
a single division of the class, in which those beings are com- 
prehended. The term /iciXa/coarpciKOc (molli crusta obtectus) 
designated, among the Greeks, those marine animals without 
blood, whose external envelope, much less solid than the testa 
of the shelled mollusca, is yet considerably more so than the 
skin of the naked mollusca. 
The Crustacea, considered under the various relations which 
their organization presents, should incontestably occupy a 
very elevated rank among invertebrated animals, and those 
which are provided with articulated limbs. They cannot be 
placed at a remote distance from the arachnida and insects, 
whose body is like their’s, symmetrical, encompassed with a 
corneous, solid, and resisting skin, which performs the func- 
tions of the skeleton in the animals of the superior classes ; 
whose members are, like their’s, composed of several distinct 
pieces ; whose eyes are always apparent, and whose genera- 
tion is bisexual. 
They are more distant from the animals of the class anne- 
lides of Lamarck, whose body is destitute of true limbs, in 
