250 POPULAR CONCHOLOGY. 



minating in a point; outer lip thin, with its 

 spiral edge sharp ; epidermis smooth, brown, 

 covered partly or entirely by the 

 glassy enamel, which, commencing 

 with the outer lip, spreads over 

 the body of the shell. 



These shells are found in Africa, 

 and are distinguished by the rude 

 ill-shapen spire, and the curious 

 ledge which separates the outer 

 lip from the body whorl. 



117. Marginella. — Shell oval, smooth; 

 spire short; right lip having a 

 thick margin ; plaits nearly equal 

 in size ; no operculum. Animal, 

 head very distinct, with a small 

 proboscis, and two tentacula hav- 

 ing eyes at the base ; foot very 

 large. — 22 species recent, and 3 

 fossil. 



These shells are often very beautifully co- 

 loured ; many have the spire exceedingly short. 

 They inhabit hot climates. The inhabitant is 

 supposed to cover its shell with its mantle, de- 

 positing successive layers of shelly matter, as 



