9 8 Memoir Sears Foundatmt for Marine Research 



7 a. Eyes minute, about same diameter as nostril. 



Ipnopidae in part (^Bathymkrops, 

 Bathytyphlops), Part 5.^' 

 7 b. Eyes well developed, much larger than nostril. 



Bathysauridae in part. Part 5.^' 

 3 b. Upper jaw reaching rearward little (if any) past eye, and ending con- 

 siderably short of rear edge of eye in most. 



8a. Snout overhanging mouth; parasphenoid bone rearward along mid- 

 roof of mouth thickly set with low teeth. 



9 a. Base of dorsal occupying only about 24—2 5 "/o of distance between 

 gill openings and origin of caudal. Albulidae, Part 3, p. 132. 

 9b. Base of dorsal occupying about 8o''/o or more of distance be- 

 tween gill openings and origin of caudal. Pterothrissidae.^' 

 8b. Snout not overhanging mouth; parasphenoid bone without teeth. 

 10 a. Rear end of base of dorsal fin separated from upper origin of 

 caudal by a distance much shorter than head. 

 I I a. Upper jaw not reaching rearward beyond front of eye; 

 teeth inconspicuous. 



Alepocephalidae in part. Part 3, p. 250.*" 

 I 1 b. Upper jaw reaching rearward about as far as rear edge of 

 eye; teeth along rear half of lower jaw large and formi- 

 dable. Esocidae, Part 4. 

 lob. Rear end of base of dorsal fin separated from upper origin of 

 caudal by a distance at least as long as head, and longer in most. 

 1 2 a. Midline of abdomen in front of anal fin armed with a 

 double series of stiff, pointed scales (scutes). 

 Clupeidae in part (Clupeinae, pp. 274—411; Pristigaste- 

 rinae, pp. 411— 438; Chirocentrinae, pp. 438— 442; Do- 

 rosomatinae, pp. 443—451), Part 3, Key pp. 259— 262.*^ 

 12b. Midline of abdomen in front of anal fin rounded; not 

 armed with a double series of scutes. 

 13 a. Origin of dorsal fin considerably anterior to mid- 

 length of trunk; pelvlcs posterior to dorsal; max- 

 imum depth of trunk equal to about 30 "/o of dis- 

 tance from gill opening to base of caudal ; head about 

 25''/o as long as distance from snout to origin of 

 caudal. Clupeidae in part (Dussumierinae, 

 pp. 262-274), Part 3, Key pp. 259-262.*^ 



37. See also Key C, la. 38. For those with adipose fin, see Key B, 13b. 



39. Sometimes included among the Albulidae. It has not yet been reported for the western side of the Atlantic, 

 but it may be expected there because it is plentiful at moderate depths along the coast of tropical West Africa. 

 For details and description, see Poll (j6: 16-25, 28, fig. 9). 



40. See also Key A, 6 a; Key €,153. 41. See also Key A, 13a. 42. See also Key A, 12 a. 



