142 



Gill-openings very wide : numerous long bristle-like gill-rakers. No pseudo- 

 branchige. Brancbiostegals numerous. 



Dorsal fin short, in the middle of the body, standing above the interval 

 between the ventrals and the anal. Anal rather long. Caudal forked. Adipose 

 dorsal small. Pectorals and anals well developed. 



A long slender air-bladder present. 



Distribution. Seas of India and New Zealand. 



Photichthys differs from Cyclothone (1) in having scales, though they are 

 thin and deciduous, (2) in the very conspicuous luminous organs, (3) in the 

 position of the dorsal fin, which stands over the space between the ventrals and 

 the anal instead of commencing opposite the origin of the anal. 



116. Photichthys corythceolus, Alcock. 



Diplophos corythxolmn, Alcock, Ann. Mag. Nat. Hist. Angast, 1898, p. 147 : Illustrations of the Zoologt or 

 THE Investigator, Fishes, pl. XXV. fig. 3. 



B. 12. D. circ. 11. A. circ. 24. P. 10. V. 7. 



Length of head about one-fourth, height of body between one-fifth and one- 

 sixth of the total without the caudal. 



The snout, which has the lower jaw prominent, is hardly longer than the 

 eye, which is not quite a fourth the length of the head. The eyes are not quite 

 a diameter apart. 



The maxillary almost reaches to the preopercular angle. There is a single 

 row of small, rather distant, acicular fangs of unequal size in either jaw, and a 

 row of close-set acicular teeth on part of the palatines ; the whole surface of the 

 mesopterygoids is studded with sharp little denticles ; and there is a fang on 

 either side of the head of the vomer. 



Gill-openings extremely wide ; four gills with short laminas ; gill-rakers, 

 especially those on the first arch, long and bristle-like. 



The body has evidently been covered with large thin and deciduous scales. 



The dorsal fin arises about an eye-length behind the base of the ventrals, 

 and its last few rays are just above the first few anal rays ; its first ray is slightly 

 nearer to the snout than to the base of the caudal. The long anal fin approaches 

 within less than half a head-length of the base of the caudal. The pectorals 

 are on almost the same plane as the ventrals, and these arise about midway 

 between the base of the former and the origin of the anal. 



The luminous organs, which are of the " bull's eye " type, are disposed as 

 follows on either side : — 



(1) one at the mandibular symphysis : 



(2) one between the bases of all the branchiostegal rays : 



