172 



meriting with a thin, fragile, pellucid, viscous matter, 

 in its first stage scarcely perceptible, but becoming, 

 by each successive deposit or layer of testaceous coat- 

 ing, thicker and more solid, till the whole is completed 

 and has attained to its full maturity. 



The propriety of Lamarck's having been guided in 

 his arrangement of the genera of shells, by the organ- 

 ization of the animal inhabiting them, and not by the 

 form of the shell only, except with a reference to the 

 inhabitant of it, need not be more fully exemplified 

 than in this instance, should any doubt still exist in the 

 naturalist's mind; and in every case the study of na- 

 ture would be much facilitated, by observing more 

 narrowly the indications she furnishes for the classifi- 

 cation of distinct genera and species, which, from be- 

 ing often so very slightly defined, are too frequently 

 overlooked or neglected, and considered of less import- 

 ance than they really are. 



Helix vesicalis 



Heli 



x mutata 



gigantea 





• pomatia 



polyzonalis 





• aspersa 



monozonalis 





• vermiculata 



pulla 





• alonensis 



lineolata 





• versicolor 





