XARCACIONTIDAE. 



•jii:; 



Narcaciontidae. 



Head, trunk, electric organs, and pectorals forming a smooth, depressed, 

 subcircular disk. Tail short, broad-based, with a short deep caudal and with or 

 without a longitudinal fold on each side. Caudal not lobed. Dorsals two, 

 one, or none. Spiracles present. Gill openings small, between the electric 

 organs and the head. An electric organ of vertical cells, a development from 

 the ampullae, at each side of the head separating it from the pectoral. Anterior 

 nasal valves reaching the mouth, confluent, and somewhat free, as a lip, behind 

 their median attachment. Antorbital cartilages extended forward to support 

 the edges of the disk. Rostrum short, more or less branching. Lateral line 

 rudimentary on the lower side of the disk, the remnants known as the vesicles 

 of Savi. Skin soft, naked. 



Two dorsals 



disk elongate 



tail long, without lateral folds 



eyes obsolescent .... Benthobatis (page 294) 



disk subcircular, of medium size 

 tail elongate with lateral folds 



ventrals distinct ; spiracles near the eyes . Narcine (page 296) 

 disk medium, circular 



tail moderate, with lateral folds 



ventrals united ; spiracles not fringed . Discopyge (page 302) 

 disk comparatively large, elongate 

 tail very short 



ventrals united ; spiracles fringed . . Hypnarce (page 303) 

 disk large, broad, subcircular 

 tail short, with lateral folds 



ventrals distinct; spiracles a short distance from eyes 



Narcacion (page 304) 

 One dorsal 



disk subcircular 



tail medium, with lateral folds 



spiracles close to the eye, not fringed . . Narke (page 312) 

 No dorsal 



disk subcircular, longer than tail 



teeth blunt, papillae behind the bands \ . Temera (page 315) 



