136 
of the different forms of the sides, multiplied by the number of different 
forms of the back, the number of species will be found far beyond 
expectation. 
The number of species is, however, not confined by even these 
limits ; since colour, another source of change, and of multiplication of 
species, remains yet to be considered. It is true, that of this source we 
cannot avail ourselves in the enumeration of fossil shells ; but it is cer- 
tainly fair to examine how far it may have been likely to have multi- 
plied the number of species of this shell, in a recent state, which, in a 
fossil state, and without this addition, we have seen to be so very 
numerous. In the genus Conus, Linnaeus admits seventy-one species ; 
and in the genus Cypreea, one hundred and fourteen species : and, in 
both these genera, the figure of the shells so approximate to uniformity, 
as to allow it to be said, that the chief of the specific distinctions which 
have been had recourse to in them, have been those of colour, varying 
in its hues, and in the forms in which it has been disposed. Reckoning, 
therefore, upon the still further multiplication of the species of this 
genus, by distinctions arising from the various differences, as to colour, 
combined with the numerous distinctions as to figure, it may be con- 
cluded, that the number of species comprised in this genus, in a recent 
state, must have been immense ; although at present we know not of 
the existence of a single individual ! 
Besides the markings observable on these fossils, which may be 
thought worthy of being regarded as specific distinctions, there is ano- 
ther kind, which is common to the whole genus, suffering some little 
variation in different species. These are the elegant undulating mark- 
ings on the surface, which are named foliaceous sutures, and which are 
seldom observable but where the external shell is removed. Unlike the 
septa of the Nautilus, the septa in the shells of this genus are always 
extended in a peculiar sinuous form ; so that, on the removal of the 
external shell, those edges of the septa, which terminated in the 
parietes of the shell, appear in very elegant forms, similar to those of 
a beautiful foliage, as is represented in the pyritous specimen, Plate IX. 
