Fishes of the IV es tern North Atlantic loi 



15 b. Upper jaw not extending rearward ap- 

 preciably beyond eye; dorsal profile of 

 head straight to weakly convex; body 

 deepest about at dorsal fin. 

 1 6 a. Origin of rayed dorsal nearer to 

 gill opening than to adipose dorsal 

 by a distance of slightly less to 

 considerably more than head 

 length. 



17a. Pupil round; entire posterior 

 edge of opercular flap formed 

 by subopercular bone. 



Aulopidae, Part 5. 

 17b. Pupil keyhole-shaped; pos- 

 terior edge of opercular flap 

 formed by opercle above, 

 and by subopercle below. 

 Chlorophthalmidae, Part 5. 

 1 6 b. Origin of rayed dorsal almost or 

 quite as near to adipose dorsal as 

 to gill opening, and much nearer 

 to adipose dorsal in some. 



Osmeridae, Part 3, p. 553. 

 lb. No rayed dorsal fin; only an adipose dorsal fin. Anotopteridae, Part 5. 



Key C. Photophores present on head, or on body, or on both; or with eyes 



on top of head. 

 I a. Eyes without lenses, covered by frontal bones, and consisting of large and flat 

 plates that occupy more than half of dorsal surface of head. 



Ipnopidae in part, Part 5.^'' 

 I b. Eyes with lenses, not covered by the frontal bones and, if dorsally directed, oc- 

 cupying less than half of dorsal surface of head. 



2 a. One or more barbels on chin, usually long and fleshy but sometimes very 

 small. 



3 a. Dorsal fin mostly or wholly anterior to anal, its origin near midlength 

 of trunk. 



4a. Dorsal base extending behind pelvics, its origin behind or only 

 slightly before pelvic base; first dorsal ray not prolonged. 



Astronesthidae, Part 4. 



52. For those without these organs, see Key A, 7 a. 



