90 TRACHELIPODA. 



Gen7^s 36— CERITHIUM 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 Pleurotoma, but the apertui-e is without tho 

 slit on the right mai-gin. 



Cerithium semigranosum — The Semigranulated Ceri- 

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

 transverse minute strise, 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 genei'a Scalaria, Turbo, and Cerithium, are nearly allied to this 

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

 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. 



