436 



THE OCEAN WORLD. 



white spots, AvWch is very common on the shores of the Medi- 

 terranean. 



The eighth family is NeritidcB, of which we may give as typical 

 genera, Ncritina, Navicella, and Nerita. The species of Nerita are 

 numerous and pretty, and are mostly marine. 



Fig. 232. — Delphinula sphaerula (Kiener). 



The ninth family, Ttirbinida, has among its more important genera 

 those of Turbo, Phasianella, Troc/ms, Delphinula, and Imperator. Of 

 Ddphinula only about seventy living species are known. They are 



Fig. 233. — Imperator Stella (Lamarck). 



Fig. 234. — Trochus stdlaris (Gmel). 



mostly natives of the Indian Ocean, and are remarkable for their 

 numerous spines and the asperity of their shells (Fig. 232). Of the 

 genus Imperator -w^ may instance die Spurred Trochus, Imperator 

 Stella, which is studded with radiating spines (Fig. 233), Imperator 

 stellaris (Fig. 234), they are natives of the Australian seas, and 

 Imperator iviperialis, commonly called the Royal Spur. 

 ., Our tenth family, lUtorinuice^ contains the genera Solarium, 



