SHELL-Fish. These animals are in general ovipa-
rous, very few instances having been found of such as
are viviparous. Among the oviparous kinds, anatomi-
sts have found that some species are of different sexes,
in the different individuals of the same species: but others
are hermaphrodites, every one being in itself both male
and female, in both cases their increase is very nume-
rous, and scarce inferior to that of plants, or of the
most fruitful of the insect class. The eggs are very
small and are hung together in a sort of clusters by
means of a glutinous humour, which is always placed
about them, and is of the nature of the jelly of frog's
spawn. By means of this, they are not only kept to-
gether in the parcel, but the whole cluster is fastened
to the rocks, shells, or other solid substances; and thus
they are preserved from being driven on shore by the
waves, and left where they cannot succeed.