B. Dorsal behind ventrals. 



1. Barbel present. 



a. No adipose fin. Origin of dorsal and anal 

 opposite. 



aa. Scaly, teeth fixed Stomias p. in. 



bb. Scaleless, teeth depressible Melanostomlas p. 113. 



b. Adipose fin present. Dorsal between ventrals 



and anal Astronesthes p. 115. 



2. No barbel. 



a. Dorsal as long as anal and opposed to it, 

 its end close to caudal. Vomer and palatines 

 without teeth. Suborbital luminous organ 



crescentic and revolving Malacosteus p. 117. 



b. Dorsal much shorter than anal, its end far 

 distant from caudal. Teeth on palatines, on 

 vomer present or absent. Suborbital luminous 

 organ not revolving, black. 



ot. Origin of dorsal in middle of length, 



situated before anal. Teeth on palatines. Vinciguerria p. 119. 

 |3. Origin of dorsal behind middle of length, 



opposite to anal. 



aa. Suborbital bone dilated, covering, at 

 least partly, the cheek. Long fang-like 

 teeth rather regularly distributed in the 

 upper and lower jaw, with much smaller 

 ones between them. Adipose fin present Gonostoma p. 1 20. 



bb. Suborbital bone not dilated, not cover- 

 ing the cheek. Teeth in jaws small, in- 

 creasing in size from before backward, 

 the posterior maxillary ones more or less 

 obliquely directed forward, sometimes 

 a few short fangs anteriorly in the 

 mandible. No adipose fin Cyclothone p. 124. 



i. Idiacanthus Peters. 



(PETERS, Monatsberichte Akad. Berlin 1876, p. 847). 



Very slender, elongate and compressed. Scaleless. Head 

 compressed, small. Snout short. Opercle narrow. Gape of 

 mouth and gillopening very wide. A long fleshy barbel behind 

 the chin. No pectorals. Ventrals before middle of body. No 

 adipose fin. Origin of the very long dorsal above or before 

 ventrals. Vent on a papilla behind middle of body, immedia- 



