262 SUPPLEMENT | 
The superficies of the whorls is also to be regarded. They 
may be designated under the name of carinated when in the 
direction of their length they present an angle or fold more 
or less marked; smooth when they have no projections or 
anfractuosities; rugose, tuberculous, when their surface is 
charged with rugosities or tubercles; striated when they are 
striped in breadth or length; trellised when this takes place 
in both directions ; corded when they are bordered by a pro- 
jecting and knotty side; costate when the pad of the left lip 
holds on the whorls, as in lyra; varicose when the continuous 
pads of the right lip are more or less tuberculous and de- 
sected, as in murex generally. 
According to the notion which we have given above of the 
formation of a spiral shell, we shall see that if the whorls 
touch not transversely, i. e. from right to left, nor from top to 
bottom, there will be perceptible in the middle of the shell a 
conical depression extending from summit to base (which is 
named wmbilicus in Latin), and at the same time a vacancy 
more or less considerable between each whorl, as in the ver- 
metus of Adanson, and in the true scalaria. ‘These shells are 
named disjuncte (disjointed.) Tf, in rolling, the convolutions 
of the cone touch each other from top to bottom, but not 
transversely, we have a shell strongly umbilicated, as in the 
scalaria; and finally, if the whorls of the spire touch in all 
directions, without encroaching, or more especially if they 
should encroach upon each other, constituting in the first case 
a complete spiral cone, or in the next an incomplete one, it 
follows that the fictitious axis is no longer free, no longer 
hollow, except sometimes at the base, and that it is replaced 
by a sort of small twisted pillar, resulting from the contact, 
and interfusion of the internal edge of the cone, on which it 
is rolled. In fact, in examining a shell of this nature from 
base to summit, we see in its interior a solid part more or less 
tortuous, to which is given the name columella, pillar in 
