260 SUPPLEMENT 
to the head, or exactly the reverse if we follow the growth of 
the shell. Those are the true spirivalve shells which we 
name turbinated. 
The name of spire (clavicula) is given to all that part of a 
spirivalve shell which is formed by the revolution of the 
spiral cone. 
That of circumvolution or whorl to a complete revolution 
of the spiral cone. 
Sometimes we distinguish from the totality of the spire the 
last whorl, which is usually the biggest, and where the aper- 
ture is found; and it is designated under the name of the 
body of the shell. The face, which is found to correspond 
to the aperture, is the Jelly, that which is opposed to it the 
back ; but Bruguiéres will have it that the belly is only that 
part of the last whorl which forms the left portion of the — 
aperture, and on which the internal lip is attached. Be this 
as it may, the name of clavicle is reserved for all the rest of 
the spire. 
The direction according to which the rolling of the spiral 
cone is made serves to distinguish the shells into right and. 
left. In general the actual termination of the shell is at the 
right of the animal, and consequently proceeding from this 
point, the volutation or torsion seems to be made from right 
to left, going from base to head: such are the normal spiral 
shells. But it happens pretty often, that the animal being 
anomalous in this respect, is, as it were inverted, that is, 
what is usually at the right is found at the left, and vice 
versa, and then the shell is equally anomalous by having its 
terminal edge at the left. These shells are called left, or 
sinistre, or heterostrophes. 
The consideration of the spire, properly so called, but taken 
as a whole, gives rise to some technical terms, which to a 
certain point are involved in those used to designate the 
general form of the shells. The spire is called 
