PULMONARY GASTEROPODS. 431 



middle of their external side. Its foot is large, bilobate in front, with 

 a semicircular horny operculum. 



The Purpuras inhabit the clefts of rocks in marine regions covered 

 with algae. On occasions they bury themselves in the sand. They 

 creep about by the help of their foot in pursuit of bivalves, which they 

 open by means of their short snout. They are found in all seas ; but 

 the larger species and greatest numbers come from warm regions, 

 more especially from the Australian seas. 



The Purpura of the ancients was not, as is generally thought, a 

 vermilion red, but rather a very deep violet, which at a later period 

 came to have various shades of red. The secret of its preparation 

 was only known to the Phoenicians, that being most esteemed which 

 came from Tyre. An English traveller, Mr. Wilde, has discovered on 

 the eastern shores of the Mediterranean, near the ruins of Tyre, a 

 certain number of circular excavations in the solid rock. In these 

 excavations he found a great number of broken shells of Murex trun- 

 culus. It is probable that they had been bruised in great masses by 

 the Tyrian workmen for the manufacture of the purple dye. Many 

 shells of the same species are found actually living on the same coast 

 at the present time. 



Aristotle, in his writings, dwells upon the purple. He says that 

 this dye is taken from two flesh-eating molluscs inhabiting the sea 

 which washes the Phoenician coast. According to the description 

 given by the celebrated Greek philosopher, one of these animals 

 had a very large shell, consisting of seven turns of the spiral, 

 studded with spines, and terminating in a strong beak ; the other had 

 a shell much smaller. Aristotle named the last* animal Buccinum. 

 It is thought that the last species is recognized in the Purpura 

 lapillus (Fig. 277), which abounds in the Channel. Keaumur and 

 Duhamel obtained, in fact, a purple colour from this species, which 

 they applied to some stuffs, and found that it resisted the strongest 

 lye. The genus Murex is supposed to have been 'the first species in- 

 dicated by Aristotle. 



Up to the present time, the production of the purple remains a 

 mystery. It was long thought this fine dye was furnished by the 

 stomach, liver, and kidneys; but M. Lacaze-Duthiers has demon- 

 strated that the organ which secretes it is found on the lower surface 

 of the mantle, between the intestines and the respiratory organs, where 



