1 04 Memoir Sears Foundation for Marine Research 



2b. Lower lobe of caudal about as long as upper lobe; gill openings broad; base 

 of pectorals not wholly above gill openings. 



3a. Upper jaw falling far short of eye; teeth minute, if detectable at all. 

 4 a. Either an adipose fin between rayed dorsal and caudal, or a dome- 

 shaped luminescent organ on eye tube. Opisthoproctidae, Part 4. 

 4 b. No adipose fin, and no luminescent organ on eye tube. 



Argentinidae in part {Xenophthalmichthys, 

 Microstomatinae in part). Part 4.^^ 

 3b. Upper jaw reaching rearward beyond front of eye; teeth fang-like, con- 

 spicuous. 



5a. Body strongly compressed sidewise, covered with scales; pectorals 

 with 19—21 rays, their line of insertion oblique, wholly above artic- 

 ulation of lower jaw with skull (quadrate bone). 



Scopelarchidae, Part 5. 

 5b. Body not much compressed, without scales; pectorals with only 12 

 rays, their line of insertion nearly horizontal, close to ventral outline 

 of body, entirely below articulation of lower jaw. 



Evermannellidae in part. Part 5.'^ 

 I b. Eyes at tips of slender stalks. 



Stalk-eyed larval stages of Bathylagidae in part (Part 4);"'' of Idiacanthidae 

 in part (Part 4);"* of Myctophidae in part (Part 5);** and probably others 

 of unknown parentage. 



62. See also Key A, 13b; Key B, 8b; and Key B, 9a. 63. See also Key B, iib. 



64. See also Key B, 9 b. 65. See also Key C, 6a. 



66. See also Key C, 14a. 



