326 PISCES. 



ORDER VI. ELEUTHEROPOMI. 



Branchiae pectinated, free, with one large external 

 aperture; furnished with an opercle, but without 

 rays in the membrane : upper jaw formed by the 

 palatine bone firmly united to the maxillary: 

 intermaxillary rudimentary. 



71. ACIPENSER Body elongated; mailed, as well 



as the head, with osseous tubercles arranged in longitu- 

 dinal rows: snout conical: mouth placed beneath, very 

 protractile, small, without teeth : nostrils and eyes lateral : 

 four pendent barbules on the under surface of the snout. 



ORDER VII. ACANTHORRHINI. 



Branchiae pectinated ; adhering by a large portion of 

 their external margin ; opening outwards by a 

 single aperture, communicating with five others at 

 the bottom of the general cavity: opercle rudi- 

 mentary : the vomer alone present to represent the 

 upper jaw. 



72. CHIMERA Body elongated: snout conic, mark- 

 ed with lines of pores : jaws armed with hard plates instead 

 of teeth ; four above and two below : between the eyes a 

 fleshy process, bent forwards, and terminating in a cluster 

 of small spines : first dorsal armed with a strong spine ; 

 placed above the pectorals : second dorsal commencing im- 

 mediately behind the first, and, reaching to the end of the 

 tail, which terminates in a long filament. 



