13 CONCHOLOGY. 



indifpenfably neceflfary to define and know 

 the animal itfelf, to fix the fpecies. This 

 objeftion, however, I do not confider as a 

 foUd one ; iiace the natnrahft mu(t know, 

 that different colours and fornis or appear- 

 ances, in the different ftages of growth, 

 run equally with teftaceous animals, 

 through all the orders of nature. Thus 

 for example: the horned quadrupeds have 

 their horns only at ftated growths ; the 

 birds, a ftated colouring of plumage ; fome 

 infecls, yet more remarkable, crawl one 

 part of their lives on the terreftial, or cut 

 the watery, before they fport in the airy, 

 element, Thefe are far greater changes 

 than any we know of teftaceous animals : 

 and therefore the abfolute neceflity to fcru- 

 tinize or define the creature by the differ- 

 ent ftages of its growth, can never, I 

 think, be demanded for them, more than 

 for any other order of animals, 



I fliall elucidate this point by the follow^ 

 ing account : Mr. Adanfon, in his Natura} 



{^iftory 



