XXI MALACOPTERYGII 57d 
but the mouth and eyes are always large, these fish being 
essentially predatory ; the dentition is often very powerful, and 
may extend to the palate or be confined to the jaws. The body 
is naked or scaly; luminous spots (photophores) are more or less 
developed.'. The development and position of the vertical fin is 
highly variable within this group, and the several families which 
have been founded upon this character have no more taxonomic 
importance than in the better-understood groups Characinidae 
and Siluridae. All authors, besides, have been compelled to 
admit that the presence or 
absence of an adipose dorsal 
fin has no high significance 
in this case, a view which 
is further strengthened by 
Dr. Gilchrist’s discovery, off 
the Cape of Good Hope, 
of a deep-sea Fish agreeing 
in every respect with <Astro- 
nesthes, but for the presence 
of a small adipose fin, ab- Fic. oO ee ae (After 
solutely similar to the dorsal, 
but situated on the ventral side, immediately in front of the anus. 
Two species with similar ventral adipose fins have just been 
discovered by Dr. Brauer and referred to <Astronesthes. I am 
therefore unable to adopt the elaborate arrangement in favour 
with the modern American school. 
The genera may be arranged in five sub-families :— 
I. Anal not exactly opposed to the rayed dorsal, or much longer than the 
latter ; no hyoid barbel. 
A. Rayed dorsal far forward, between pectorals and ventrals ; pectorals 
well developed (CHAULIODONTINAE). Chauliodus. 
B. Rayed dorsal above or behind the ventrals ; pectorals well developed. 
1. Body more or less elongate ; ventrals well developed (Gonostoma- 
TINAE). 
a. A hyoid barbel.  Astronesthes. 
b. No barbel. Bathylychnus, Gonostoma, Cyclothone, Triplophos, 
Photichthys, Bathylaco, Diplophos, Maurolicus, Ichthyococcus. 
2. Body short and deep; ventrals rudimentary or absent (STERNOPTY- 
CHINAE). Argyropelecus, Sternoptyx, Polyipnus. 
II. Dorsal and anal opposed to each other and very far back on the 
caudal region ; pectorals often reduced or absent ; hyoid barbel often present. 
1 See above, p. 178. 
