152 CONCIIOLOGY. 



columella covered over v^^ith a broad, smooth callosity, uni- 

 ting behind to the right edge ; operculum horny. 



Cassidaria echinophora. Cassidaria cingulata. 



C. Tyrrhena. C. striata. 



C. oniscus. 



C. echinophora. The tuberculated Cassidaria. PI. 27, 

 fig. 5. 



Species oval, sub-globular, canal sub-ascendant, with tu- 

 berculated belts or ribs. 



C. Tyrrhena. The Tyrrhenian Cassidaria. 

 Species ovate, grooved transversely, volutions convex; 

 ^pex with one tubercle ; tawny colour. 



2. Cassis. The Helmet Shell. Twenty-five species. 

 This genus was formed from the Buccinum, from which 

 it is easily distinguished ; the latter having only a notch at 

 the base, and the Cassis with a canal abruptly turned towards 

 the back of the shell. 



Shell inflated oval, subrinvolute, spire very little projecting; 

 aperture long, oval, sometimes very narrow, terminated an- 

 teriorly by a very short canal, sloped and recurved obliquely 

 towards the back ; the right edge more or less concave, re- 

 flected backward, and often dentated within ; the columella 

 covered with a large callosity, denticulated or wrinkled iu 

 all its length ; operculum horny. 



Cassis cornuta. Cassis crumena. 



C. tuberosa. C. plicaria. 



C. Madagascariensis. C. areola. 



C. flammea. C. zebra. 



C. fascinata. C decussata. 



C. glauca. C. abbreviata. 



C. rufa. C. sulcosa. '. 



C. pennata. C. granulosa. 



C. testiculus. C. saburon. 



C. achatina. C canaliculata, 



