82 PBOVISIONAL AID TO THE STUDY OF TASMANIAN MOLLUSCA. 



Sub-Genus Mamilla. Schum. (Exjma, H. and A. Adams.) 



Shell ovate, conic, rather thin, with pointed spire ; whorls 

 fasciated ; mouth oblong ; inner lip narrow, reflected ; 

 umbilicus not funicula-ied. 



Genus Sigabetus. Lam. (178.) 

 Shell ear-shaped, with minute spire, and very large aperture, 

 externally with revolving stria', colour usually white, 

 with sometimes a thin corneous epidermis ; operculum 

 minute, horny, sub-spiral. Dist. — United States, 

 West Indies, China, Peru, Australasia. 



Genus Lamellabia. Montagu. (179.) 

 Shell ear-shaped, thin, pellucid, fragile ; spire very small ; 

 aperture large, patulous ; inner lip receding ; no 

 operculum. Dist. — Norway, Great Britain, Medi- 

 terranean, New Zealand, Philippines. 



(xxiv.) Family CALYPTRMDiE. 

 (Shell limpet-like, with the apex more or less spiral ; interior 

 simple, or divided by a shelly process or plate, variously 

 shaped, to which the adductor muscles are attached.) 



Genus Infundibulum. Montfort. (180.) 



Syn. — Trochita, Clypeola, Trochella. 



Shell conic trochiform, spiral ; summit central ; whorls 

 convex, plicate not umbilicated ; aperture large, con- 

 taining a spiral, transverse lamina or plate, extending 

 obliquely from the centre to the outer margin of the 

 shell. Dist. — Mostly tropical and sub-tropical. 



Genus Calypte^a. Lam. (182.) 

 Shell conical, more or less angular, with sub-central sub- 

 posterior sharp apex ; aperture basal, with a central 

 lamina, half-cup shaped, attached to apex and open in 

 front. Dist. — World-wide. 



Genus Legeandia. Beddome. (181.) 



Shell emarginuliform ; internal plate like Crepidula ; radiately 



ribbed ; front edge fissured. Dist. —Tasmania. 



Genus Crepidula. Lam. (183-184) 

 Shell oval, limpet-like, with a posterior generally lateral spiral 

 apex ; interior with a shelly plate covering its posterior 

 half. Dist— World-wide. 



