170 PECTINIBRANCHIATA.—CYPRAEADA. 
Some naturalists have supposed that the cowries, 
precluded, as it appears, (beyond a certain point) 
from enlarging their shells in the usual manner by 
the increase of the last whorl, have the power of 
forsaking their shells, and of forming new ones of 
larger size, as a crab or lobster sloughs its crust. 
Others believe that a process of gradual absorption 
and deposition will meet the necessities of the case, 
which, however, it must be confessed, presents con- 
siderable difficulty. 
The earliest stage of life im these animals, as, 
we believe, in all the Gasteropoda, however diverse 
their adult condition may be, appears under the 
form of a nautilus-like shell, the inhabitant of 
which is furnished with two large-winged lobes, by 
which it is able to swim freely. Mr. Arthur Adams 
thus describes the young of one of the cowries :— 
‘“ While staying at Singapore, I had an opportunity, 
in conjunction with Dr. Trail of that place, of ob- 
serving the fry of Cyprea annulus, the species being 
then in spawn. Several specimens collected by us 
at low water, were seen to have conglomerated 
masses of minute transparent shells, adhering to 
the mantle and other parts of the animal, which 
masses, when placed in a watch-glass of salt water, 
under the microscope, became disintegrated, and 
detached individuals were perceived quitting the 
rest, and moving in rapid gyrations, with abrupt 
jerking movements, by means of two rounded 
flattened alar membranous expansions, reminding 
one of the motions of some of the Pteropods. 
When at rest, they jomed the principal mass, or 
adhered, by means of their dilated expansions, to 
the surface of the watch-glass.” * 
* Zool. of Samarang, Part III. p. 23. 
