TROCHUS. 7 



generally carinated at the periphery, sometimes rounded, more or 

 less flattened beneath ; aperture rhomboidal, very oblique ; columella 

 twisted, its edge generally folded or dentate, generally toothed at 

 base ; sculptured usually with spiral beaded ridges. The species are 

 all old world in distribution. 



Subgenus Trochus, (sensu stricto.) 



Shell large, thick, solid, the spire pyramidal or conical, periphery 

 angulated, base flat or convex ; outer and basal lips smooth within, 

 the columella with a strong fold above, ending in an obtuse tooth 

 below\ T. uiloticus L., etc. 



Subgenus Cardinalia Gray, 1857. 



Shell conical ; base plano-concave, Avithout false-umbilicus ; outer 

 lip smooth within ; columella short, arcuate, simple, Avithout a fold 

 above, ending below in an acute denticle. 



Indo-Pacific Province. 



Subgenus Tectus Montfort, 1810. 



Shell pyramidal ; base flat, without false-umbilicus ; aperture 



rhomboidal, very oblique, angular, wider than long ; outer lip lirate 



Avithin ; columella very short, vertical, with a strong spiral fold, 



ending anteriorly in a knob or point. Type, T. mauritianus Gniel. 



Indo-Pacific Province. 



Subgenus Infundibulum Montfort, 1810. 

 Shell conical, false-umbilicate ; columella more or less folded 

 above, its edge straight, oblique, toothed or simple, with or without 

 a tooth at base. Type, T. concavus Gmel. 



Indo-Pacific and Australasian Province. 



Section Lamprostoma Swainson, 1840. 



Shell conical with nearly flat base and angular periphery ; all 

 over granose-lirate ; columella tortuous above, its edge denticulate; 

 basal and outer margins of aperture generally lirate within. Type, 

 T. maculatus Linn. 

 Section Infundibulum (sensu str.). 



Shell conical, periphery angular, base nearly flat, or concave ; 

 outer surface smooth, costate or granular ; outer lip not lirate with- 

 in ; columella inserted in the center of the axis, strongly folded 

 above, its edge smooth, not toothed nor notched at base. Type, T. 

 concavus Gmel. 



