CYCLOSTOMID^. 
17 
Fam. 1. CYCLOSTOMIDJE. 
The gills are vascular^ branched^ lining the inside of 
the mantle, the outer edge of which is free 
from the back of the neck ; the eyes are sessile, 
on the outer side of the base of the tentacles ; 
male organs hidden in the hinder part of the 
cavity under the edge of the mantle. Mantle 
with a thin edge. Jaw none ; vent on the 
right side of the edge of the mantle. Foot 
broad, body central spiral, enveloped in a simple 
edged mantle, which is covered with an ovate 
spiral shell, with a roundish mouth, and fur- 
nished with a spiral operculum. 
Fig, 1. 
Cyclostoma elegans. 
d, showing the under side of the foot, divided into two parts. 
e, operculum. 
These animals live on vegetable matter, like the 
snails, and are found in damp places on a chalky soil. 
C 
