160 

 Scopelus, Cuv., Giinther. 



Scopelus:, Giinther, Cut. Fishes, V. pp. 404, 405 ubi synon. 



Myctophidie (exo. Nannobrachium and Scopelosaurus) Goode and Bean, Oceanic Ichthyology, p 70, and Jordan 

 and Evermann, Fishes N. Amer., pp. 551, 5.52. 



Body moderately elongate and compressed, covered with large scales of 

 which those of the lateral line are generally the largest. Series of luminous 

 spots run along the lower side of the head body and tail, and a luminous body 

 often occupies the snout and the back of the tail. Head generally compressed, 

 with the bones thin but ossified. Cleft of the mouth very wide : premaxilla long, 

 styliform ; maxilla well developed. Villiform teeth in bands in the jaws, on the 

 palatines pterygoids and tongue, and sometimes on the vomer. Eye large. 



Dorsal fin short ; in, or nearly in, the middle of the back ; anal short or of 

 moderate length. Caudal forked. Adipose fin small. Pectorals and ventrals 

 well developed, the latter inserted in front of, or below, the anterior part of the 

 dorsal, and eight-rayed. 



Gill-opening very wide, the outer branchial arch with numerous long gill- 

 rakers. Branchiostegals from 8 to 10. Pseudobranchia? present. 



Air-bladder small. Pyloric caaca few. 



Distribution : Pelagic and Nectic. 



The Indian species of this genus are now known to be nine in number. 

 Two of them, however, are represented in the Investigator collections only by 

 specimens recovered from the stomach of other fishes, and are too much damaged 

 for recognition. The remaining seven fall into the following sub-genera. 



Indian sub-genera of the genus Scopelus. 



I. Snout deep, short, rounded : dorsal fin just in advance of the anal : pseudo- 

 branchiffi well developed : the anal fin with as many rays as, or more rays 

 than, the dorsal: eye large : scales smooth. ... ... ... Myctophum. 



II. Snout rather long, somewhat depressed, not rounded : dorsal fin a consider- 

 able distance in advance of the anal : the anal fin with as many rays as, 

 or more than, the dorsal : — 



1. Pseudobrauckioe well developed : eye moderate : scales with minute 



spines ... ... ... ... ... ... Neoscopelus. 



2. Pseudobranchia? rudimentary : eye small. (Scales unknown) ... Scopelengys. 



Key to the Indian species of the sub-genus Myctophum. 



I. A large luminous mass on the snout immediately in front of the orbit : 

 pectorals short : — 



1. The pectorala do not reach to the base of the ventrals : all the 

 phosphorescent spots are divided by a median transverse black 



septum ... ... ... ... ... ... S. engraxdis. 



2. The pectorals reach just beyond the base of the ventrals : phosphores- 

 cent organs without a black septum ... ... ... S- dumerilii. 



