28 CLASS MOLLUSC A. 



would become too great for its possessor. To guard 

 against this inconvenience, and this useless waste of 

 material, the creature possesses the power of absorbing 

 so much of the substance of what now becomes the 

 internal portion of its dwelling as is unnecessary for its 

 present use, and of re-depositing the same on the outward 

 wall of its mansion, where strength is most required*. 



The Cones, says Lamarck, are the most beautiful of 

 all the univalve shells ; the genus comprises the most 

 valuable and the most remarkable specimens of this 

 family, whether we look at the regularity of their form 

 or the splendour of their colours. The beauty of many, 

 but, above all, the extreme rarity of others, have given 

 them a species of celebrity, and have caused them to be 

 much sought after by collectors. 



Oliav porphyria. 



^ The Cones are found in the seas of hot climates, in 

 from ten to twelve fathom water. The animal of the 

 Cones has the head furnished with two tentaculse, or 

 hoins, with the eyes on the summits ; they only inhabit 

 salt waters. 



* This is one of the rare exceptions to the usual plan resorted to by 

 natiu'e in the f oi m ation of a shell, as noticed in the introductory chapter. 



