GASTEROPODA. 239 



before was plain. The outer surface of these shells 

 presents in consequence a high polish resembling 

 that of china-ware ; and the whole appearance is so 

 altered, that the young Cowry, which presented the 

 common form of an oblong-oval, turbinated shell, 

 would never be recognised in its mature figure and 

 texture. They chiefly inhabit the tropical seas, and 

 one little species, perhaps the most common of all, 

 the Blackamoor's tooth (C. Moneta), is extensively 

 used as money in Africa and the Oriental Archipe- 

 lago. 



In other genera, the adult figure sometimes differs 

 greatly from that of its early stages, as in some of 

 the Strombi ; in Pterocera * Scorpio, the edge of the 

 mouth, which before was small and entire, enlarges 

 into a broad expansion, extending even all up 

 the spire, and shoots out many finger-like projec- 

 tions, which at first are hollow, but gradually become 

 solid by the deposition of stony matter in their inte- 

 rior. 



Patella^ the Limpet. 



A few genera, of which the one before us affords 

 a good example, vary from the preceding in the 

 structure of their shell, which does not ordinarily 

 assume a spiral form ; but resembles an oval, somewhat 

 conical cup, inverted, in the concavity of which 

 dwells the animal, in no very material point differing 

 from the forms we have noticed. In some species, 



* n<rov, pteron., a wing, and x,'iu,s t keras, a horn, 

 t Patella, a little dish. 



