CLASS PISCES. 621 



fishes have the appearance of having only lateral 

 jaws, like the insects or the nereides, which caused 

 them to be ranged by Linnaeus in the class of worms. 

 But all the rest of their organization is analogous 

 to that of the Lampreys ' ; their tongue performs in 

 the same manner the office of a piston, and the dorsal 

 spine is also in the form of a cord. The mouth is cir- 

 cular, surrounded with eight barbels, and at its upper 

 edge is pierced an air-hole, which communicates with 

 its interior. The body is cylindrical, and furnished 

 behind with a fin, which surrounds the tail. The 

 intestine is simple, and straight, but wide, and folded 

 internally. The liver has two lobes. We find no 

 traces of eyes. The eggs grow to a large size. 

 These singular animals shed through the pores of 

 their lateral line such an abundance of mucous matter, 

 that they appear to convert into jelly the vases in 

 which they are kept. 



They attack and pierce fishes like the Lam- 

 preys. 



They are subdivided according to the external 

 orifices of their gills. 



In 



Heptatremes, Dum. t 



There are still some holes on each side, as in the 

 Lampreys. 



But one is known, from the South Sea, Gastro- 



1 See the Memoir of Abildgaart, Ecrits de la Soc. des Nat. de 

 Berlin, torn. x. p. 193. 



