45 <S 



THE OCEAN WORLD. 



small flat head, furnished with lateral tentacles or horns, bearing the 

 eyes upon an external swelling, situated near their central length. 

 ^Ve need only refer to Fig. 288, Buccinum senticostim, and Biicdmim 

 iindatum, the well-known whelk of our markets (Fig. 289), for their 

 general form. 



The genus Harpa contains shells from the Indian Ocean, richly 

 enamelled within, and ornamented externally with slightly oblique 

 longitudinal stripes in gay colours, with finely-sculptured forms in the 

 intervals ; spire very small, and opening large. Among the more 



Fig. ago. — Harpa ventricosa (Lamarck). 



Fig. 291. — Harpa imperialis (Lamarck). 



attractive species are HarMi ventricosa (Fig. 290), Harpa impcrialis 

 (Fig. 291), and Harpa ariiciilaris (Fig. 292). 



The fifth family, Mjiricidce, contains Fiisus, Pyrula, Triton, and 

 Alurex. 



The genus Murex, or Rock Shells, include a large number ol 

 species, all remarkable for their bright colours and somewhat fantas- 

 tical and varied forms. They are found in all seas, but become 

 larger and more branching in the seas of warm regions. The shell 

 is oval, or rather oblong, the spire more or less elevated, its surface 

 generally covered with rows of spines, or tubercular ramifications. 

 The opening, which is oval, is prolonged in a straight canal, often of 

 very considerable length, as in Murex haustellum (Fig. 293) ; the 

 external edge is often smooth or rippled, the columellar edge some- 

 times callous. 



