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



93 



Sub-Genus Tuebo. (Restricted.) 

 Shell smooth, or tuberculate, covered by a smooth epidermis ; 

 inner lip flattened, more or less produced in front ; no 

 umbilicus, operculum spiral on its inner face, convex 

 and smooth or granular (not ridged) externally. 

 Sub-G-enus Senectus. Humph. 

 Shell solid, with revolving squamose or spinose ridges 

 covering the whorls; axis usually narrowly -perforated; 

 aperture usually slightly produced in front, with 

 sometimes a short channel. 



Sub-Genus Mabmobostoma. Swains. 

 Shell thick, smooth or tuberculate; aperture rounded in front; 

 columella callus covering the axis, which is umbilicated, 

 however ; the umbilicus often at the upper end of a 

 curved channel in the callus; operculum spiral, with 

 central nucleus, and an indistinct sub-central external 

 rib. 



(xlv.) Family Teochim. 

 (Shell usually conical, with flattened base, nacreous inside ; 

 operculum corneous, multispiral.) 



Genus Teochus. Linn. (343-388.) 

 Shell pyramidal, with nearly a Eat base ; whorls, numerous, 

 flat, variously striated ; aperture oblique, rhombic, 

 pearly inside ; columella twisted, slightly truncated ; 

 outer lip thin ; operculum, horny, multispiral. Dist — 

 World-wide ; low water to 15 fathoms, the smaller 

 species to 100 fathoms. 



Sub-Genus Teochus. (Restricted.) 

 "Umbilical region excavated but not perforated ; columella 

 spirally twisted above, terminating in a point anteriorly. 

 Sub-Genus Infundibulum. Mont. (Caeinidea. Swains.) 

 Shell, conical ; whorls flattened, the last angular, base concave ; 

 columella without teeth, or teeth obsolete. 

 Sub-Genus Minolia. A. Adams. 

 Shell globosely conoidal, widely and profoundly umbilicated ; 

 whorls rounded, clathrate ; suture canaliculate ; last 

 whorl, subsolute towards the aperture; umbilicus 

 perspective ; aperture circular, pearly within ; peristome, 

 continuous, thin, acute. 

 Sub-Genus Astele. Swainson. (Tas. Journal, 1855.) 

 Shell nacreous, pyramidal or trochiform ; unarmed ; body 

 whorl convex ; columella, none ; umbilicus large, closed 

 only by the terminal whorl of the spire ; aperture, 

 broader than high, the margin of both lips thin. 



