BY B. M. JOHNSTON, F.L.S. 



81 



Sub-Genus Teivia. Gray. 

 Distinguished by being striated over the back, frequently 

 interrupted by an impressed dorsal sulcus. 



Sub-Genus Cypb^e-ovttla. Gray. 

 Pyriform, oval, ventricose. Surface covered with revolving 

 strife. 



Genus Ovulxtm. Brug. (1G5.) 



Shell ventricose, convolute, attenuate, and sub-acuminate at both 



ends ; outer lip of adult thickened and inflected. 



Sub-Genus Volva. Bolten. 

 Distinguished by being ventricose in middle, and in having 

 both extremities prolonged into canals. 



(xxii.) Family CASsroiDiE. 

 Genus Cassis. Lam. (166-170.) 

 Shell sub-globular or triangular, usually solid, thick (Tas- 

 manian species excepted), last whorl large, varicose ; 

 aperture longitudinal, narrow; outer lip with a 

 thickened, reflected margin, dentate within ; inner lip 

 rugosely plicate ; operculum oval, narrow, with median 

 apex. Dist. — Mostly tropical and sub-tropical ; vora- 

 cious, living in sandy localities, preying upon bivalve 

 molluscs. 



Sub-Genus Sbmicassis. Klein. 

 Shell oval, with revolving ribs ; spine moderate, sharp. 



Sub-Genus Casmaeia. H. and A. Adams. 

 Shell generally smooth; whorls simple or sub-plicate, spire 

 moderate ; inner lip smooth, callous ; outer lip 

 margined, smooth or slightly crenulated on the inner 

 edge. 



(xxiii.) Family Naticid^. 

 (Shell globular or oval ; spire, usually short ; aperture, semi- 

 lunar, without canal or anterior notch ; outer lip sharp ; 

 columella callous, more or less reflected over the umbilicus ; 

 operculum pauci-spiral, corneous, or with an exterior 

 calcareous layer.) 



Genus Natica. Lam. (171-177.) 

 Shell sub-globular ; spire slightly elevated ; aperture half 

 round. A spiral columella callus entering the umbilicus. 

 Dist. — World-wide. 





