Fishes of the Western North Atlantic ()() 



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 if^/o as great 

 as distance from gill opening to base of caudal; 

 head between 17— 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. 



3 a. 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.''* 

 4b. 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. 



6 a. 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 93; Key D, 4 b. 44. For those without dorsal adipose fin, see Key A, 5a. 



45. See also Key D, 4 b. 



7* 



