32 
Pyramidella. — Shell turreted; no epidermis: aperture entire, demi-oval; outer lip sharp. 
Columella produced, subperforate at the base, and furnished with three trans- 
verse plaits. 
Plate XVI. Fig. 9. P. terebcllum. 
SCALARIANA 3 Genera. 
Shells without plaits on the columella ; the margins of the aperture circularly united. 
Vermetus. — Shell thin, tubular, loosely spiral, adhering by the spire: aperture orbicu- 
lar, the margins united. An operculum. 
Plate XVI. Fig. 10. V. lumbricalis. 
Scalaria. — Shell subturreted, ornamented with longitudinal, elevated, interrupted, near- 
ly acute ribs : aperture rounded, the margins circularly united, and terminated by 
a thin, recurved varix. 
Plate XVI. Fig. 11. S. pretiosa, (Turbo scalaris. — Linn.) 
Delphinula. — Shell subdiscoidal, or conical ; umbilicated, solid ; whorls rough or angu- 
lar: aperture entire, round, sometimes triangular; the margins united, mostly 
fringed or ventricose. 
Plate XVI. Fig. 12. D. laciniata. (Turbo delpliinus. — Linn.) 
TURBIN ACE A 8 Genera. 
Shell turreted , or conoidal; the aperture round, or oblong, not effuse; the margins disunited. 
Solarium. — Shell orbicular, depressed-conical, umbilicated, crenulated or dentated on 
the inner margin of the whorls: aperture nearly quadrangular. No columella. 
Plate XVI. Fig. 13, 13 (a). S. perspectivum. (Troclius perspectivus. — Linn.) 
Rotella. — Shell orbicular, shining, no epidermis; spire very short, sub-conoidal; lower 
surface convex and callous : aperture semicircular. 
Plate XVI. Fig. 14, 14 («). R. lineolata. (Trochus vestiarius.— Linn.) 
Trochus. — Shell conical; spire elevated, sometimes rather depressed; periphery more 
or less angular, often thin and sharp; aperture transversely depressed; the mar- 
gins disunited at the upper part; columella arched, more or less prominent at the 
base. An operculum. 
Plate XVI. Fig. 15. T. virgatus. (Idem. — Gmel.) 
Monodonta. — Shell oval or conoidal : aperture entire, round, the margins disunited at 
the upper part ; columella arched, truncated at the base. An operculum. 
Plate XVI. Fig. 16. M. labio. (Troclius labio. — Linn.) 
Turbo. — Shell conoidal, or subturreted; the periphery never compressed: aperture 
entire, round, not modified by the penultimate whorl; the margins disunited at 
the upper part; columella arched, flattened, not truncated at the base. An 
operculum. 
Plate XVI. Fig. 17- T. pica. (Idem.— Linn.) 
