146 THE CHITON. 



uncovered, and which has various patterns in the differ- 

 ent species. 



Thus has an outline of the structure of the gastero- 

 poda been attempted, so far, at least, as is warrantable 

 in a cursory notice like the present ; and this plan has 

 been followed the rather, because in no department of 

 natural history does so mistaken an idea generally prevail 

 as to the mode in which these animals ought to be 

 studied. It is customary, indeed, to attend to their shells 

 alone — to collect them, and arrange them according 

 to their form, and to keep them thus arranged in cabi- 

 nets — the study of these outer vestments being dignified 

 with the name of Conchology. But what science is 

 there, in taking up a shell, and calling it helix, or bulla, 

 or cyprsea ? In such a pursuit a child of good memory 

 will make rapid progress. We do not say that the 

 shells ought to be neglected, for their form and colour- 

 ing lead to the establishment of species ; but unless 

 we know something of the organization of the animals 

 by which they are formed, our information is very con- 

 tracted — it is to know the house, but not the inmate — 

 the casket, not the jewel — the cover of a volume, but 

 not the contents. Pursued as a true science, the study 

 of the shelled mollusks is one of great interest ; it in- 

 troduces us to a world of wonders, from the contempla- 



