90 TRACHELIPODA. 



Genus 36.— CERIT HIUM Bruguiere. 



Generic Character. — Shell turreted ; aperture oblong, 

 oblique, terminated at the base by a short, truncated, re- 

 curved canal, without a notch ; the outer lip with a groove 

 at its upper extremity; aperture provided with a small 

 horny operculum. 



This genus is allied to Pleui'otoma, but the aperture is without the 

 slit on the right margin. 



Cerithium semigranosum. — The Semigranulated Ceri- 

 THiUM. Plate XII. fig. 9. Fusiform, turreted ; apex acute ; 

 transverse minute striae, and sulcated granulations; the suture 

 with double spiral rows of large granules ; colour reddish- 

 brown. One inch and a half long. Inhabits the seas of 

 New Holland. 



Section II. — Phytiphaga. 



Without a projecting siphon, generally respiring by an 

 orifice ; provided with jaws, and usually feeding on vege- 

 table substances; shell having the aperture entire, and des- 

 titute of a notch or canal. 



FAMILY I. TURBINACEA. 



Shell turreted, or conical, with an oblong or rounded 

 aperture, not expanding, and the margin disunited. 



Genus 37 TURRITELLA — Lamarck. 



Generic Character Shell turreted, not pearly; aperture 



rounded, entire ; margin disunited above ; the outer lip 

 with a slight sinus, and the aperture furnished with a horny 

 operculum. 



The genera Scalaria, Turbo, and Cerithium, are nearly allied to this 

 genus, but may easily be distinguished from them by a sinus on tho 

 right margin of the apei-ture, which is only visible when the mouth is 

 quite perfect, and which does not exist in any other shells. 



