128 CONCHOLOGY. 



S. lineatus. S. marginatus. 



S. turritus. S. cancellatus. 



FAMILY XIX. 

 PuRPURiFKRA. Eleven genera. 

 1. Genus Cassidaria. PI. XII. 

 Animal. Somewhat elongated, widened anteriorly ; mantle 

 with simple edges and provided with a distinct tube ; foot very 

 wide, elliptical, sub-bilolate anteriorly, and having a large opercu. 

 lum upon the dorsal face of its posterior part ; head wide and in- 

 distinct ; tentacula anterior, approximating at base, sub-cylin- 

 drical, and having the eyes at two-thirds of their length ; mouth 

 inferior, concealed by the foot ; two pectiniform branchiae, nearly 

 parallel. 



Shell. Sub-globular, tuberculated or channelled, with a short 

 pointed spire ; aperture long, ovate, subcanaliculated anteriorly ; 

 right edge folded I ack ; columella covered by a wide smooth 

 callosity uniting posteriorly with the right edge. Inhabits all 

 seas except the Northern. Five living species. Seven fossil. 

 Cassidaria echinophora. Cassidaria striata. 



C. Tyrrhena. C. oniscus. 



C. cingulata. 



2. Gei^us Cassis. PI. X"II. 



Animal. Spiral, with the foot (which is shorter than the shell) 

 rounded anteriorly ; mantle provided, before the respiratory cavity, 

 with a long open canal, used as an organ of prehension ; head 

 furnished; a single pair of blackish tentacula, having the eyes at 

 an inflation about half v/ay from the base ; mouth armed v^'ith a 

 proboscis. 



Shell. Inflated, oval, subinvolute ; spire slightly projecting ; 

 aperture long, oval, sometimes very narrow, terminated anteriorly 

 by a very short canal, sloped, and flexed obliquely towards the 

 back; columella covered by a large callosity, indented throughout 

 its length ; operculum horny. Found in the Indian, Mediterra- 

 nean, and Equatorial seas. Twenty-five living species. Eight 

 fossil. 



