UNIVALVE MOLLUSCA. 



459 



The head of the animal is furnished with two horns or tentacles, 

 with ocelli upon their external side, the mouth elongated in the form 

 of a proboscis. The foot is large and round, and furnished with a 

 horny operculum. 



Among the species with long slender tube, covered with spines, 

 one of the most notable is Murex tenuispina (Fig. 294), which is a 

 native of the Indian Ocean and the Moluccas. 



Fig. 292. Harpa articularis Fig. 293. Murex haustellum Fig. 294. Murex tenuispiua 

 (Lamarck). (Linnaeus). (Lamarck). 



Among the strong-tubed species with long canal and no spines, from 

 the same regions, is Murex haustellum (Fig. 293). 



Among the short-tubed species, furnished with foliaceous and 

 jagged fringes, is Murex scorpio (Fig. 295). 



One more typical species may be noted, namely, Murex erinaceus 

 (Fig. 296), which is found on all the coasts of Europe, and especially 

 in the British Channel. Other species worthy of notice are found in 

 the Mediterranean and Adriatic, some of them, according to Cuvier 

 and de Blainville, species which furnished the true Tyrian purple of 

 the ancients \ but our space prevents us from dwelling on them. 



