^j, OF CARTILAGINOUS FISHZS. 



the animal kingdom. It would appear that they are ca** 

 pable of fubfifting indifcrlminatelj in either of thefe two 

 elements, to each of which the fl;ru6lure of their parts 

 feem to have a reference ; it was no doubt this afpe£l of 

 the cartilaginous filhes, which prefented itfelf to LiTtmeus 

 when he arranged them in the fame order with thofe ani- 

 mals, properlj amphibious *, that are capable of fublilling 

 either in the water or in the air. Of this power, however, 

 this clafs of beings is by no means poffefTed ; for, though 

 they are capable of fupporting life for a longer time on 

 fhore, tha < the fpinous fifbes, yet there is hardly any of 

 them that can live there above a few hours at a tiraef. 

 Whatever, therefore, be the ftrufture of their organs, 

 there is none of them properly amphibious, or that jufllj 

 merits a place among that order of beings. 



But although the double llru£ture of the organs of 

 refpiration in the cartilaginous fiflies, will not juflify us 

 in placing them among the fiihes, tortoifes, lizards, and 

 other animals that are ftriftly amphibious, it forms, 

 however, a very palpable mark of diftindlion between 

 them and the cetaceous fiflies on the one hand, and the 

 fpinous upon the other ; from the latter they are known, 

 becaufe, though they have apertures correfponding to 

 gills, they univerfally want the bony operctila which co- 

 vers ihem %, 



Thefe apertures by which they breathe, are placed al- 

 ways near the head, but have not uniformly the famepo- 

 fition : In fome they are placed benearh, as in the rays, 

 and other flat filli j in others on the fides, as among the 



Ihark 



* He has termed them aniohibia names. Vide Syftema Naturs^ 



* Willough. Ictliyol. 



i Pennant's Brit, Zool. Clafs iv. Div. ij. 



