MALACOPTERYGII 



571 



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- 

 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). Ghauliodus. 



B. Rayed dorsal abov^ 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, Gyclothone, Triploplios, 

 Photichthys, Bathylaco, Diplophos, Maurolicus, Ichthyococcus. 



2. Body short and deep ; ventrals rudimentary or absent (Sternopty- 



CHINab). Argyropelecus, Sternoptyx, Polyipniis. 



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. 



' See above, p. 178. 



Tig. 346. — Sternoptyx diaphana. 

 Giintlier.) 



(After 



