CYCLOSTOMID^:. 



17 



Earn. 1. CYCLOSTOMID^E, 



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 



