166 "ENDEAVOUR'' SCIENTIFIC RESULTS. 



GG. Anal fin longer, with 20 or more rays. 

 H. Lateral photophores terminating 

 above or before the ventral 

 fins. 



I. Ventral photophores united 



with anteroanals. 



Argyripnus. 



II. Ventral photophores separated 



from anteroanals. 



Maurolicus. 

 HH. Lateral photophores extending 



backward to near vent. 

 J. Entire dorsal fin far in 

 advance of anal; mandible 

 and palate with long fangs. 

 Photiclithys. 



JJ. Posterior dorsal rays above 

 anterior anal rays; jaws 

 and palate without large 

 fangs. 



Polymetme. 



BB. Three or more rows of photophores on each side. 



Lynchnopoles, Diplophos, and Triplophos. 



POLYMETME gen. nor. 



Body elongate, apparently scaly. Bones of head thin 

 and loosely joined. Mouth wide, the upper jaw largely 

 formed by the maxilla, which extends backward almost 

 to the preopercnlar angle; mandible projecting beyond 

 the upper jaw when the mouth is closed. Teeth well 

 developed, but without enlarged fangs; two rows on the 

 premaxillaries and mandible, and one on the maxillary; 

 teeth on the vomer and palatines with teeth. Gill- 

 openings very wide; gill-rakers slender; no pseudo- 

 branchiae. Photophores very conspicuous, in two rows 

 on each side of the abdomen and in one from the vent 

 to the caudal fin. Dorsal fin short, above the interspace 

 between the ventral and anal fins; its posterior rays 

 above the origin of the anal; adipose dorsal present. 

 Anal fin long, with 24-29 rays. Caudal forked. Pectorals 

 and ventral s well developed. 



Type. P. illustris sp. nov. 



This genus is closely allied to PliotlcJithys Gtinther, 

 but differs in its dentition and in having the dorsal fin 

 placed somewhat farther back. Photichthys has 

 several canines in the premaxillaries, and about seven 

 longer fangs on each side of the mandible ; a small canine 

 on each side of the vomer, and each palatine bears a long 



