130 MANUAL OF NATURAL HISTORY. 



20. FAMILY. Pyramid-Shells (Pyramidellidse). 



Tentacles ear-shaped; eyes on their inner 

 sides ; mantle enclosed ; foot moderate ; shell 

 turreted ; columella plicated. 



21. FAMILY. Eulimas (Eulimidse). Tentacles 



simple, subulate ; eyes on their outer bases ; 

 mantle enclosed ; foot moderate ; shell tur- 

 reted ; columella simple. 



22. FAMILY. Star-fish Parasites (Stylinidse). Foot 



greatly produced in front ; tentacles subulate, 

 simple : eyes on their outer bases ; mantle 

 enclosed; shell globose or turreted ; aperture 

 oblong columella simple. Parasitic on Star- 

 fishes. 



23. FAMILY. False Club-Shells (Cerithiopsidae). 



Eyes on centre of tentacles at their base ; 

 mantle enclosed, with a short siphon; foot 

 grooved beneath ; operculum with the nu- 

 cleus apical ; shell turreted, granular ; aper- 

 ture with a short anterior canal. 

 24 FAMILY. Stair case -Shells (Architectonicidse). 

 Tentacles folded, with the suture below ; eyes 

 sessile on upper surface of their base ; ten- 

 tacles close together at their base; foot small ; 

 operculum ovate or circular ; shell trochiform, 

 with a wide umbilicus. (Solarium, Lamck.) 



II. S UB-ORDER. ROSTRIFEROUS-PECTINIBRANCHS 

 (Rostrifera). 



Head with a non-retractile rostrum ; tentacles 

 subulate, wide apart, on the sides of the rostrum. 

 Mostly phytophagous. 



