COWRY. 
583 
they furnish the ordinary exterior layers of enamel, 
upon which we may perceive the marks of the la- 
minae or successive coats of which all shells are com- 
posed. The shape of the exterior layers is different 
from those situated beneath, which may be consi- 
dered as a smooth shining substance that the animal 
goes over once while it is forming its shell in order 
to give it the necessary solidity. It is from the 
body of the animal, or from the edge of its collar, 
that the inferior part of the shell is formed, or rather 
the testaceous mould. This mould is generally thin 
and very brittle: it is striated longitudinally; and as 
its origin is not different from that of other shells, it 
is not surprising that we find proofs of the formation 
in the regular projections which the extremities of 
the layers leave by the side of each other, fhe co- 
lours of the mould are different from those of the 
exterior layers, and it frequently shows the trans- 
versal bands with which it is marked, whilst the 
enamel is adorned with spots or stains, because some 
parts of the body of the animal are disposed to fur- 
nish this composition, which is secreted from certain 
moist glands of a different kind from those of the 
wings. 
Thus we remark two distinct operations in 
the formation of a cowry : the first is that which 
produces the part of the shell which we have called 
the mould, and is the result of a secretion from the 
body of the animal; the second, the formation of the 
shining enamel. The cowries are thin and transpa- 
rent in the first stages of their growth, but at length 
