ORDER PECTINIBRANCHIATA. 69 
transmitting the siphon or tube, which is itself but an elon- 
gated fold of the mantle. ‘The greater or less length of the 
canal, when there is one, the size of the aperture, and the 
form of the columella, furnish the grounds of its division into 
genera, which may be variously grouped. 
Conus, L., 
So called from the conical shape of the shell ; the spire, either 
perfectly flat, or but slightly salient, forms the base of the 
cone ; its point is at the opposite extremity ; the aperture is 
narrow, rectilinear, or nearly so, extending from one end to 
the other, without enlargement or fold, either on its edge or on 
the columella. The thinness of the animal is proportioned 
to the narrowness of the aperture through which it issues. 
Its tentacula and proboscis have great capacity of elongation. 
The eyes are placed on the outer side of the former, and near 
the point ; the operculum, situated obliquely on the hind part 
of the foot, is too narrow and short to close the whole of the 
aperture. 
In placing here the genera with a straight aperture, we must 
not be understood as meaning to approximate them to the 
preceding family, but only to present them first, as possessing 
the most striking characters of all those which are furnished 
with a siphon. 
The shells of this genus being usually ornamented with the 
most beautiful colours, are very common in cabinets. The 
seas of Europe produce very few. 
They are distinguished by the flatness or slight projection 
of the spire; by the whorls being tuberculated or not; by its 
being more salient, and even pointed, and furnished, or not, 
with tubercles. 
There are some in which the spire is sufficiently salient to 
give them a cylindrical appearance, in which case it may be 
