116 GASTEOPODA. 



FAMILY V. FISSUEELLAD^. 



Shell limpet-shaped, summit turned backwards ; 

 a slit in the front margin, or a perforation at the 

 summit. Animal with a distinct head, eyes, and 

 tentacles ; gill-plumes two. 



Fissurella (Lamk.). Key-hole Limpet. Shell oval, 

 conical, low, with the summit perforated. 



F. reticulata. Fig. 168 ; J n. s. 



Puncturella (Lowe). Shell conical, high, with 

 the summit turned back ; perforation in front of 

 the summit. 



P. Noachina. Fig. 169 ; n.s. 



Emarginula (Lamk.). Shell high, with the sum- 

 mit turned back ; front margin slit. 



E. crassa. 1X 



reticulata. Fig. 170 ; _2 

 rosea. 



FAMILY VI. HALIOTID.E. 



Shell spiral, ear-shaped, or snail-shaped, with 

 a wide aperture, the outer lip either perforated or 

 slit. Animal with a short muzzle, tentacles, and 

 eyes ; gill-plumes two. 



Haliotis (Linn.). Ear-shell; Ormer. Shell ear- 

 shaped ; spire minute, flat ; aperture very wide, in- 

 terior pearly ; margin perforated with many holes. 

 Animal with fringed lobes to the head and sides ; 

 no operculum. 



H. tuberculata. Fig. 171 ; \n.s. 



