4 



striae also remaining so that the species might be readily 

 distinguished. 



A valve of a Chiton from the Red Sea, weighing 

 eighteen grains, lost seventeen in the process, but the 

 grain that remained, while it was wet, retained all the 

 marks of the original shell. In this experiment the 

 solution was not attended with so rapid an extrication 

 of gas as in the two former. Ten grains of the Bulla 

 hydatis, on the contrary, being subjected to the same 

 test, left merely a white transparent film. 



This striking difference in the composition of the 

 shell of the Chiton from that of other Testacea, added 

 to its general appearance, will furnish sufficient grounds 

 to dispute its title to its present situation, but the plan 

 of this work being strictly to follow the Linnaean ar- 

 rangement, the Author has not hesitated to commence 

 his specifications with this genus. 



In the twelfth and last edition of the Systema Naturae 

 by Linnaeus, we find but nine Chitons enumerated. 

 Gmelin, in his enlarged edition, has noticed twenty- 

 eight, and the reader will perceive that in the present 

 work, the number has been still further increased, by 

 the addition of several new species. 



