150 



PISCES. 



Myxine (Linn.) . Hag. Cylindrical ; an orifice 

 [spiracle) on the head ; mouth round, surrounded 

 by eight filaments, and armed with one tooth ; 

 dorsal along the back, continued round the tail to 

 the vent. 



M. glutinosa. Fig. 218 ; -| n.s. 



Petromyzoii (Linn.). Lamprey. Cylindrical; 

 gill-openings seven on each side of the neck ; 

 mouth round, armed with many teeth ; dorsal as 

 in Myxine. 



P. marinus. Fig. 219 ; ^ n.s. 



220 



Order 11. BEL A CHI A . 



Skeleton complete ; jaws (formed of the palatal 

 and post-mandihular bones) armed with teeth ; 



