ISO MANUAL OF NATUKAL 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 (Eulimidae). 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 (Cerithiopsidse). 



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. — Staircase -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 — Postriferous-Pectinibranchs 

 (Postrifera). 



Head with a non-retractile rostrum ; tentacles 

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

 Mostly phytophagous. 



