6 THE ELEMENTS 



shell into the fire, it will begin to 

 crackle and divide in separate layers. 

 We have numberless instances of 

 shells, both sea and land, which have 

 been broken, and are firmly mended 

 by the animal ; and in almost every 

 collection specimens of mended shells 

 may be found. 



Shells are only the habitation of 

 soft animals called vermes, or worms, 

 and are the third order of Linnaeus's 

 sixth class of animals. 



The animals which have been dis- 

 covered to inhabit shells, are ten : 



1. Limax, 6. Nereis, 



2. Doris, 7. Ascidea, 



3. Spio, 8. Tethys, 



4. Am phi trite, 9. Triton, 



5. Terebella, 10. Sepia. 



1st. LIMAX. 



Body oblong, creeping, with a 

 fleshy kind of shield above, and a lon- 

 gitudinal flat disk beneath ; aperture 



