Sir Everard Home on the 
298 
of the 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 necessary 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 in a dried 
state, containing the young shells completely formed, are to 
be met with in collections of natural history ; but I am 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 
Indies saw the chank (a shell belonging to the same genus 
with th evoluta pyrum of Linnaeus,) shed its eggs, that the ani- 
mal discharged a mass of mucus, adapted to the form of 
the lip of the shell, and several inches in length ; this rope 
of eggs, enclosed in mucus at the end which is last dis- 
engaged, 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 membranous structure, so that the 
eggs became enclosed in membranous chambers, and the 
nidus having one end fixed and the other loose, was moved 
by the waves, and the young in the eggs, had their blood 
aerated ; when the young were hatched, they remained de- 
fended 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 al- 
though what I have stated was communicated to me by an eye 
witness, it required confirmation, as well as an opportunity 
