136 



of eye from half to two-fifths the length of the head. A small spine at the 

 posterior corner of the mandible, and another at the angle of the preoperculum. 

 Tail without spines. 



The pectoral fin extends nearly to the origin of the anal. 



Bay of Bengal, 1803 fathoms. 



Distribution : Atlantic, Mediterranean, Bay of Bengal. Regd. No. 13119. 



Besides the " Investigator " specimen there are several specimens from the 

 Mediterranean in the Indian Museum. 



Sternoptyx, Hermann. 



Sternoptyx, Hermann, Naturforscher, 1781, XVI : Cnvier & Valenciennes, Hist. Nat. Poiss. XXII., p. 412 : 

 Giinther, Cat. Fishes, V., p. 386, and Challenger Deep-Sea^Fishes, p. 168: Gootle and.Bean, Oceanic Ichthyology, 

 p. 123 : Jordan and Evermann, Fishes N. Amer., p. 603. 



Form of the body as in Argyropelecus, but with a peculiar drag downwards 

 and forwards, and with the wide corner between the ventral angle of the trunk 

 and the tail filled up by a curious transparent fold of skin supported by long 

 interhaemal rays. Body covered with a skin like that of Argyropelecus, but not 

 quite so brilliant. Series of luminous organs as in Argyropelecus, but less 

 conspicuous and less " bull's-eye "-like. The middle line of the belly between 

 the humeral and pelvic spines is trenchant, not serrated. 



Mouth as in Argyropelecus, but not quite so wide : palatines toothless. 



Eyes large, lateral, without any upward cast. 



Gill-opening wide : a few rather distant gill-rakers on the outer side of the 

 first branchial arch are elongate. Branchiostegals five. PseudobranchiaB present. 



Dorsal fin short, situated farther back than in Argyropelecus, preceded by a 

 thin triangular osseous plate which has a serrated edge but no series of indepen- 

 dent spines. Anal long, extending from near the vent to near the caudal ; its 

 rays are feeble. Caudal forked. The anal is preceded by a pair of little spines 

 similar to those at the pectoral and pubic symphyses. 



Pectorals well developed, not far from the ventral profile. Ventrals small. 



Distribution : Atlantic, Arabian Sea, Western Pacific. 



112. Sternoptyx diaphana, Hermann. 



Sternoptyx diaphana, Hermann, see Giinther, Cat. Fishes, V., p. 387 aud Challenger Deep-Sea Fishes, p. 169, 

 pi. xlv , figs. D, D' : Vaillant, Exp. Sci. Travaillenr et Talisman, p. 102 : A. Agassiz, Hull. Mus. Comp. Zool. XV., 

 p. 22, fig. 195 : Goode and Bean, Oceanic Ichthyology, p. 124, fig. 146 : Jordan and Evermann, Fishes, N. Amer., 

 p. 603: Collett, Hirondelle Poissons (Monaco, 1896), p. 125. 



B. 5. D. 9-12. A. 12. P. 10. V. 3. 



Greatest height of the body twice that of the tail (not including the trans- 

 parent fold that fills up the corner between the tail and the belly), and more 



