OX CRUSTACEA. 
265 
the tail bears underneath two oval bodies, sufficiently distant 
from each other, and which appear to give rise to two small 
organs, which the elder M. Juriue presumes to be those of 
generation. Each of them is composed of three rings, which 
diminish in size. The second furnishes two or three threads ; 
and the third is terminated in a point. 
With respect to the products of generation, the Crustacea 
are either oviparous or ovo-viviparous. The eggs which they 
lay have a corneous envelope, solid, and usually transparent, 
through which the gum may sometimes be perceived. These 
eggs, developed in a liquid conduit, which in its bottom part 
receives the name of ovary, and in its most external portion 
that of oviduct, are small, often very numerous, of a spherical 
or oval form, and present, according to the species, very vari- 
ous colours. 
After they issue from the body, they are usually carried for 
a longer or a shorter time by the females, sometimes under 
the tail, attached by filaments, resembling, from the desicca- 
tion of the viscous matter which invests them, two peculiar ap- 
pendages, which have received the name of false feet, as is the 
case with crabs and astaci; sometimes between leaflets, at the 
base of which the gills are fixed, as in certain isopods; 
and sometimes, in fine, in an exterior membranaceous en- 
velope, forming an ovary or external matrix, as in cyclops 
and branchipes, or in a dorsal cavity, as in daphnis and 
lynceus. 
In certain genera they disclose the young while } r et con- 
tained in the body of the animal, or in the dorsal cavity which 
wc have just mentioned, as is remarked in Argulus and Daph- 
nis, which, in consequence of this phenomenon, are distin- 
guished from the other Crustacea, as being ovo-viviparous. 
The little ones which issue from the eggs are, in the 
generality of the Crustacea, altogether similar to their parents ; 
yet sometimes they differ so much from them, that they have 
