APPENDIX. No. III. 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 thuse 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 In- 

 dies saw the chank (a shell belonging to the same genus with 

 the valuta pj/riim of Linnasus,) 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 

 eggs, 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 



