PULMONARY GASTEROPODS. 



417 



The eighth family is Neritidse, of which we give as types, Pileolus 

 and Nerita. The hoof-shells, or Nerites, are numerous and pretty, and 

 in external form approach Turbo. 



Of the Delpliinula only a small num- 

 ber of living species are known. They 

 are natives of the Indian Ocean, and 

 remarkable for their numerous spines and 

 the asperity of their shell (Fig. 233). 



The ninth family, Paludinidse, con- 

 tains Ampullaria, the idol snail of India, 

 and the widely distributed Paludina. Fig - 233 ' M P" Mta >P herula < Kienpr ). 



Our tenth family, Ltttorinidte, contains Solarium, and the peri- 

 winkles, Littorina and PJiorus, example, P. Conchyliophorus 

 (Fig. 224). 



The genus Imperator belongs to the Turbinidte, and as examples 

 of it we may instance the Spurred Trochus, Imperator stetta, which 

 is studded with radiating spines (Fig. 234), and Imperator stellaris 

 (Fig. 235) ; they are natives of the Australian seas. Imperator 



Fig. 231. Imperator stella (Lamarck). 



Fig. 235. Trocbus stellaris ((Jmel). 



imperialis, vulgarly called the Eoyal Spur, and Troclms or Eotella 

 Zealandica (Fig. 230), the New Zealand Spur, the spiral turns of 

 which are sculptured in descending furrows, and studded with im- 

 bricated scales, which form a projecting edging round the margin of 

 the shell, and give it a radiating form. This species is of a violet 

 brown above and white below, and is still rare in collections. 



The Sun-dial (Solarium}, recognized by its deep umbilicus, wide 

 and funnel-shaped, in the interior of which may be seen the little 

 crenated teeth which follow the edge of every turn of the spiral up 



2 E 



