340 



CHAP. VIII. 



OF THE SHELL OF TESTACEOUS FISHES. 

 BEFORE we enter into the history of shell-fish, it 

 may not appear improper to observe that Naturalists, 

 who have written upon this part of history, have en- 

 tirely attended to outward forms ; and, instead of giving 

 a description of the animal, have confined themselves 

 wholly to the account of its shell. 



The shell of a fish may properly be considered as an 

 habitation which Nature has bounteously supplied, con- 

 sisting of a hard stony substance, formed somewhat in 

 the manner of a wall : part of this stony substance is 

 derived from outward objects, whilst the fluids in the 

 animal's body furnishes the cement : and these, united, 

 make that firm covering which shell-fish generally re- 

 side in until they die. 



The diversity is so great, both in the form and colour 

 of shells, that the study of them has constituted the 

 chief employment of some mens' lives ; and the amaz- 

 ing expense attending these collections it is difficult to 

 describe, and can scarcely be conceived. Sea-shells 

 are either found in the depths of the ocean, or, for- 

 saken by their inhabitants, are cast empty upon the 

 shore ; others are discovered in fresh-water rivers, 

 whilst the pc ^sors of some exist only upon land. 

 Naturalists have varied in their method of distinguish- 

 ing shells; but Aristotle has divided them into three 

 tribes : the turbinated, or those of the snail kind ; the 

 bivalved, or those of the oyster kind ; and the mul- 

 titalvcdy or those of the acorn-shell kind. 



