OF FISHES IN GENERAL. iZ 



No philofopher feems yet to have made obfervatlons 

 fufficientlj accurate, fully to determine this matter; for 

 it is not yet afcertained, whether the neck of the canal 

 be fupplied with a valve to emit air fecreted from die 

 blood, or to receive it from the flomaeh, or with a 

 mufcle that may equally ferve to admit, or eje£l it : And 

 what militates againft Needham^s opinion, is, that the 

 cartilaginous fifhes, which have nothing of this kind to 

 aid their digeilive powers, are as remarkable for voracity 

 as any other kind. 



The other ufe to which naturalifts have deftined this 

 organ is, to ferve as a receptacle for air, iiVilead of the 

 lungs in terreftrial animals, by which the neceflities of 

 thefe creatures may be fupplied. The air bladder of 

 fifl.ies is confined in a triangular fpace at the upper part 

 of the abdomen, and confifts of one, two, and foractimes 

 three divifions, all feparated from the refl of the vifcera 

 by a thin membrane, attached, on each fide, to the ribs; 

 An apparatus of this kind, though we be not able to 

 explain its ufe, no one can imagine was formed in vain. 

 It is poflible, that it may ferve fome purpofe different 

 from any of the above, and probably more than one 

 even of thefe. 



Fillies thus fitted for motion in their element, hy their 

 internal flrudlure, as well as by their outward fiiape, and 

 the lituation of their fins, fcem as well furnifhed with 

 the means of happiuefs, as eitlier quadrupeds or birds. 

 Like thefe they are furnifhed with an external covering, 

 to defend them from injuries in the turbulent fluid which 

 they inhabit. 1 hat flimy and glutinous fubllance, which is 

 fecreted from the pores of all filhes, not only defends 

 their bodies from accident, but is happily contrived to 

 give little obl^ruftion to their progrcfs through the wa- 

 ter, Eefides this fubllance, which defends their bodies 



B 2 froro 



