107 
B. Dorsal behind ventrals. 
1. Barbel present. 
a. No adipose fin. Origin of dorsal and anal 
opposite. 
izes SCA L YS EEL | fERO piej ia) jo at au cl pl foe's) ariel Stomias p. X11. 
46. Scaleless, teeth, depressible ...... . . .< Melanostomias p. 113. 
6, Adipose fin present. Dorsal between ventrals 
AH PATER CS teh cho ciley oi ysl ows s/s OS saat ADs casts £S 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 
Grescenticuand eVOlwID Oe ieme | eater ops Malacosteus p. 117. 
4. 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. 
a. Origin of dorsal in middle of length, 
situated before anal. Teeth on palatines. Vinciguerria p. 119. 
@. 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 Gorzostoma p. 120. 
4é. 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. 
1. 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- 
