THE TRUE FISHES. 



175 



other known bony fishes in having six pairs of internal bnnchial clefts, 

 and consequently five pairs of gills. It has no swimming-bladder. 



FIG. 217. Argyropelecus hemigymnus, twice natural size, snowing groups 

 of luminous organs. 



FIG. 218. The Pelican fish (urypharynx pelecanoides). 



