STROMBID.E. 257 



like those of the former sub-orders ; the rostrum of the 

 StromhidcB is also eloncrated, but it is alwavs easily known 

 from the retractile proboscis of the former group. 



Fam. STROMBID.E. 



Lingual membrane with seven rows of teeth (S'TS), the 

 central teeth single, the lateral three on each side, the 

 inner ones tridentate, the outer simple and uncinate. 

 Muzzle produced, longly conical ; eyes on thick, elon- 

 gated peduncles J tentacles on the middle of the eye- 

 pedicels, or none. Mantle with the outer side generally 

 expanded and often lobed. Foot narrow, compressed, 

 used for jumping not walking, divided into a front dilated, 

 and a hind tapering portion. 



Operculum ovate and simple, or claw-like and serrated. 



Shell with the outer lip changing in form with age ; 

 when adult, more or less expanded and deeply notched at 

 the fore part, or stright and simple. 



The StromhidcB are active, muscular, and pedacious 

 animals, using their opercula as weapons of defence, and 

 progressing by means of successive leaps, which they 

 accomplish by placing the narrow part of the foot under 

 the shell as a lever, and suddenly straightening it, so as 

 to throw the shell forwards. Their eyes are well-de- 

 veloped, having both pupil and iris, the latter often beau- 

 tifully coloured. The Stromhus gigas is occasionally 

 used as an article of diet ; it sometimes produces pearls, 

 and is extensively employed in the manufacture of cameos 

 and of porcelain. 



VOL. I. L L 



