290 HELICID^. 



A. Mouth furnished with teeth and folds : onter lip sinuous 

 or notched : inner lip thickened. 



1. CocHLicoPA tri'dens*, Pultenej. 



Turbo tridens, Pvilt. Cat. Dors. Sh. p. 46, pi. xix. f. 12. Azeca tridens, 

 F. & H. iy. p. 128, pi. cxxv. f. 9. 



Body greyish-slatecolour with a faint tinge of yellow, closely 

 covered with small black specks, which impart a dusky or 

 sooty hue, strongly wrinkled : mantle rather thick, milk-white 

 or greyish : tentacles somewhat transparent ; upper pair verj- 

 slender, with bulbs occupying about one-fifth ; lower pair 

 rounded at their extremities : foot long, rounded in front and 

 slightly projecting beyond the mouth of the shell ; sides edged 

 with white, and minutely speckled with milk-white ; tail very 

 pointed. 



Shell subcylindrical or shaped like a chrysalis, nearly trans- 

 parent, very shining and of almost an opaline lustre, light 

 yellowish-brown with a tinge of red, faintly and indistinctly 

 wrinkled in the line of growth and marked with extremely 

 minute spiral lines, which are only perceptible by the aid of a 

 powerful lens : periphery rounded in the adult, but sharply 

 and strongly keeled in young specimens : epidermis very thin : 

 ivhorls 7, rather tumid, the last and preceding whorl being 

 nearly of equal breadth, and much larger in proportion than 

 the others, which form a blunt cone : spire produced, rounded 

 at the point : suture slight, with a transversely wrinkled border : 

 mouth narrow, angularly curved or channeled at the base and 

 subtruncate in the young, and also channeled at the upper 

 angle ; it is still further contracted by the teeth or plate-like 

 folds, which are as foUows : — one principal fold on the pillar, 

 which is twisted round the inner lip, its crest sometimes notched, 

 and extends like a screw far into the interior, and there is 

 usually also a second smaU tooth or denticle close to the prin- 

 cipal fold and nearer the outer lip ; a strong fold winding 

 round the pillar lip, the end of which appears like a sharp and 

 prominent tooth ; and a sharp tooth -like tubercle on the 

 middle of the outer lip and placed on the inside edge of this 

 lip ; besides this last, there are occasionally two small and 

 scarcely" perceptible denticles placed below it : outer Up) sinuous 

 and (as well as the inner lip) encircled by a narrow rib, which 



* Having tliree teeth. 



