APPENDIX, No. II. 403 
garden snail, but in the testacea that live in water, the young 
requires some defence in the period, between the egg being 
hatched, and the young acquiring its shell, which is not neces- 
sary in those that live on land; for this purpose, the ova are 
enclosed in chambers of a particular kind. 
This camerated nidus in the larger animals of this tribe, must 
be familiar to all naturalists, since specimens ina dried state, 
containing the young shells completely formed, are to be met 
with in collections of natural history; but Iam not aware that 
all the purposes for which such a nidus is supplied by nature, 
have ever been explained. 
I have been informed by a friend, who while in the East In- 
dies saw the chank (a shell belonging to the same genus with 
the voluta pyrum of Linneus,) shed its eggs, that the animal 
discharged a mass of mucus, adapted to the form of the lip of 
the shell, and several inches in length’; this rope of eggs, en- 
closed in mucus, at the end which is last disengaged, was of so 
adhesive a nature, that it became attached to the rock, or stone 
on which the animal deposited it. As soon as the mucus came 
in contact with the salt water, it coagulated into a firm mem- 
branous structure, so that the eggs became enclosed in mem- 
branous chambers, and the nidus having one end fixed and the 
the other loose, was moved by the waves, and the young in the 
egos, had their blood aerated ; when the young were hatched, 
they remained defended from the violence of the waves, till 
their shells had acquired strength. 
What passes under the sea, few naturalists can be so fortunate 
as to have an opportunity of observing, and although what I 
have stated was communicated to me by an eye witness, it re- 
quired confirmation, as well as an opportunity of examining 
the nidus, before I could give it my assent. Since that time, I 
