180 200LOGY. 



1. Petromyzon. Lamprey. Body Eel-shaped, slender; 



breathing apertures seven on each side ; a fistulous 

 opening on the top of the head ; mouth situated beneath ; 

 teeth numerous, placed in circular rows ; pectoral and 

 ventral Jins y^diniYttg, 



2. Gastrobranchus. Hag-Fish. Body slender, carinated 



beneath ; mouth at the extremity, furnished with cirri, 

 and numerous teeth ; eyes wanting ; tail surrounded bj 

 a soft rayless fin, Avhich extends under the belly; spi- 

 racles two, situated on the abdomen. 



3. Raja. Ray. Body broad, thin, and flat ; apertures five 



on each side, situated beneath ; mouth beneath, trans- 

 verse, toothed. 



Many of this genus grow io a vast iize, they are voracious, 

 and devour animal substances of all descriptions, that fall in 

 their way, they mostly reside at the bottom of the water, 

 and feed principally on other kinds of flat fish ; some are 

 applied to the purpose of food ; but the flesh of the larger 

 part is rank, ill flavourd, hard, and dry ; they are caught by 

 the hook and line, also in nets. 



4. Squalus. Shark. Head obtuse ; mouth situated far 



beneath the end of the nose ; teeth numerous, moveable, 

 placed in rows ; body cylindrical, tapering towards the 

 tail ; dorsal fins two ; upper part of the tail longer 

 than the lower ; apertures five on each side. 



Thij is a very extensive genus, principally confined to th« 



