GROWTH AND HABITATION. 13 



remove with ease whatever presents an obstacle to their 

 convolutions of growth. In the Murex cornutus, for example, 

 this mode of operation may be occasionally traced, by ob- 

 serving on the left side of the aperture the base of a spine, 

 which had evidently been taken away for the purpose of 

 covering the boundary of the aperture with a coating of 

 enamel. The Cowry can even form a new shell when fully 

 grown : a phenomenon which modern naturalists long hesi- 

 tated to receive ; but which is now proved beyond doubt by 

 Lieut. Hankey, who was himself an eye-witness of the curious 

 fact, and who relates that he has seen the shell of a Cowry, 

 when too small for its occupant, begin to crack and swell ; at 

 which time some powerful solvent or decomposing fluid had 

 evidently been distributed over its outer surface by that all- 

 important instrument, the mantle ; for it gradually became 

 more dull in colour and thin in substance, till at length the 

 shell disappeared, and the Cowry was rendered homeless. 

 Short time, however, elapsed before the creature set to work, 

 and secreted a. thin layer of glutinous matter, which in a 

 few days assumed the fragile consistency of shell-lac. The 

 dwelling then rapidly progressed, till at length it was 

 consolidated into one of those beautifully spotted shells, 

 which equally ornament the widow^s cottage, cherished as 



