io6 



with auditory organ. Gillrakers moderate, short or wanting. 

 Luminous organs (photophores) on head and body. 



Synopsis of the subfamilies. 



A. Luminous organs separate, not united in groups. Body 

 very low and elongate. No pseudobranchiae. Gill- 

 rakers short or wanting Stomiatinae p. 106. 



B. Luminous organs in groups. Body generally short and 

 elevated. Pseudobranchiae present or absent. Gillrakers 



well developed (always?) Sternoptychinae^. 128. 



i. Subfam. Stomiatinae. 



Body very low, elongate and compressed. A mandibulary 

 barbel present or absent. Eye generally large. Gape of mouth 

 very wide, oblique. Dorsal generally short or by exception long, 

 its origin before or behind ventrals. Adipose fin, if present, 

 above or behind anal. Pectorals may be absent, if present, 

 very low down. A praeanal adipose fin may be present. 

 Ventrals well developed or even long. Caudal forked, its lobes 

 often unequal. Scales, if present, very thin, deciduous, cycloid 

 and sometimes rhombic. Minute teeth in jaws, those of the 

 intermaxilla and mandible may be all or in part enlarged and 

 even fang-like; on palate present or absent. Luminous organs 

 always separate. There may be opercular luminous organs and 

 others before, below and behind eye, the lastnamed even revol- 

 ving. Some between the branchiostegal rays. On the body a 

 complete ventral series between isthmus and caudal and a more 

 lateral one reaching not so far. Scattered between them and 

 on the body there may be smaller luminous organs as well 

 as whitish punctiform organs on the fins. Branchiostegal rays 

 8 20. Gillmembranes free from isthmus. Gillrakers well deve- 

 loped, short or wanting. Gills 4. No pseudobranchiae. 



Artifical key to the genera. 



I. No pectorals. Origin of long dorsal far in advance of 



anal, its end above anal. No adipose fin Idiacanthus p. 107. 



II. Pectorals present. 



A. Dorsal between pectorals and ventrals. Barbel rudi- 

 mentary. Adipose fin present Chauliodus p. 109. 



