18 
NOMENCLATURE. 
Columella. Pillar ; the middle column abou^ 
which the wreaths form their spiral cir- 
cuit. 
abrupt a. Abrupt : truncate at the base. 
caudata. Caudate; elongated so as to project 
beyond the body. 
plana. Flat ; extending into a plain lip. 
plicata. Plicate ; marked with transverse folds. 
spiralis. Spiral; caudate and spirally twisted. 
CosT^. Ribs ; keel-like processes reaching from 
the apex to the periphery of the shell. 
fornicates. Arched ; beset longitudinally with 
hollow scales. 
Digiti. Claws; digitate or finger-like lobes of 
the outer lip. 
Dorsum. Back ; the upper part of the body 
when laid on the aperture. 
Epidermis. Skin: a membranaceous covering 
of the shell, found on some but not on all 
species. 
Genicula. Geniculations ; the contraction 
of the whorls so as to correspond with the 
internal divisions or dissepiments. 
