414 



THE OCEAN WORLD. 



antly. Some of these thick, cone-shaped shells are extremely beautiful, 

 being richly nacred inside, and remarkable for the beauty and diver- 

 sity of colour exhibited. G enerally smooth, the great spiral is, never- 



Fig. 219. Trochus niloticus (Limisous). 



Fig. 221. Trochus inennis (Gmel.). 



Fig. 220. Troclnjs virgatus (Gmel ). 



Fig. 222. Trochus Cookii (Chemnitz). 



Fig. 223. Trochus imbricatus (Gmel.). Fig. 224. Phorus couckylitphorus (Borfu). 



theless, sometimes edged with a series of regular spines. The form is 

 conical, the spiral more or less raised, broad and angular at the base ; 

 the opening entire, depressed transversely, and the edge disunited in 

 the upper part. 



The animal which inhabits this shell is also spiral ; its head is fur- 

 nished with two conical tentacles, having at their base eyes borne on 

 a peduncle ; its foot is short, round at its two extremities, edged or 



