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 ; J n.s. 



Petromyzon (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 ; 



Order II. SELA CHIA. 



Skeleton complete ; jaws (formed of the palatal 

 and post-mandibular bones) armed with teeth ; 



