Fishes of the Western North Atlantic C)() 



1 3 b. Origin of dorsal fin considerably posterior to mid- 

 length of trunk; pelvics below or anterior to dorsal; 

 maximum depth of trunk only about i5''/o as great 

 as distance from gill opening to base of caudal; 

 head between i'j-2o''/o as long as distance from 

 snout to base of caudal. 



Argentinidae in part (Microstomatinae), Part 4.*^ 



Key B. a dorsal adipose fin present close in front of caudal; no photophores 



ON SIDES OF head OR BODY. 



I a. Well-developed rayed dorsal fin and adipose dorsal fin present. 



2 a. A narrow, posteriorly-pointing fleshy lobe close above base of pelvic fin on 

 each side. 



3a. Teeth in jaws well developed, easily felt; 19 or more scales in a transverse 



series from origin of dorsal to lateral line. Salmonidae, Part 3, p. 457. 



3b. Teeth in jaws minute, if present; not more than 13 scales in a transverse 



series from origin of dorsal to lateral line. Coregonidae, Part 3, p. 547. 



2 b. No fleshy lobe on side above base of pelvic fin. 



4 a. Some of upper pectoral rays longer than others and separate from lower 

 part of fin, thus forming a separate division. 



Bathypteroidae in part. Part 5.^* 

 4 b. Pectorals not divided into an upper and lower division. 



5 a. Dorsal high, sail-like, its base extending from close behind gill 



openings nearly to adipose fin. Alepisauridae, Part 5. 



5 b. Dorsal not high and sail-like, its base occupying not more than 



about half the distance between level of gill openings and adipose fin. 



6a. Upper jaw not reaching rearward as far as front of eye. 



7a. Mouth at least twice as long as eye; eye not more than 

 about i7''/o of hi (less than this in most); anal base at least 

 1.5 times longer than base of dorsal; teeth well developed, 

 long and fang-like in some. Paralepididae, Part 5. 



7b. Mouth not longer than eye; eye 27— 40''/o of hi; anal base 

 not appreciably longer than dorsal base; teeth minute, if 

 detectable at all. 



8a. Lateral-line scales not extending out onto caudal fin; 



adipose dorsal anterior to rear end of base of anal fin. 



9a. Gill membranes separate; branchiostegal rays 5 



or 6. Argentinidae in part (Argentininae), 



Part 4.« 



43. See also Key B, 8 b and 9a; Key D, 4b. 44. For those without dorsal adipose fin, see Key A, 5a. 



45. See also Key D, 4 b. 



7* 



