183 



and sometimes covering it; right lip acute, always smooth inside. An 

 operculum. 



Ianthina. Shell ventricose, conoidal, thin, transparent; aperture trian- 

 gular; columella straight, passing beyond the base of the right lip, which has 

 a sinus in the middle. No operculum. 



I. communis, I. exigua. 



MACRO STOMIANA.— Four Genera. 



Shell ear-shaped, the aperture much dilated, the margins disunited, no col- 

 umella, no operculum. 



Sigaretus. Shell subauriform, nearly orbicular; the left lip short and 

 spiral; aperture entire, much dilated, rounded, oblong; the margins not united. 



S. haliotoideus, S. concavus, S. laevigatas, S. cancellatus. 



Stomatella. Shell orbicular, oblong, ear-shaped, imperforate; aperture 

 entire, large, sublongitudinal; right lip effuse, dilated, open. 



S. imbricata, S. sulcifera, S. auricula, S. planulata. 



' rubra, 



Stomatia. Shell ear-shaped, imperforate, spire prominent; aperture 

 entire, large, oblong; right margin and columella equally raised; a transverse 

 and tuberculated rib on the back. 



S. phimotis, 



S. obscurata. 



Haliotis. Shell ear-shaped, mostly flattened ; the spire very short, 

 sometimes depressed, nearly lateral; aperture very large, ovate oblong, and 



