Fishes of the Western North Atlantic 97 



may be referred to in different parts of the same key or in one or more of the other 

 keys. For example, such of the Bathypteroidae as have no adipose dorsal fin are 

 found in Key A while those with an adipose fin are found in Key B. 



General Key to Families of Isospondyli, Iniomi, and 

 Giganturoidei of the Western North Atlantic; Adolescents and Adults^^ 



I a. Eyes (if any) of the usual sort, i. e. not at tips of slender stalks or with pupil above 

 center, and not capable of being directed upward. 



2 a. No luminescent organs (photophores) either on sides of body, or on head. 



3 a. No adipose fin between rayed dorsal fin and caudal. Key A, below. 



3 b. Adipose fin present between rayed dorsal and caudal. Key B, p. 99. 



2b. Luminescent organs (photophores) present on head, or on body, or on both; 



or with eyes on top of head. Key C, p. loi. 



I b. Eyes at tips of slender stalks, or with pupil above the center and capable of being 



directed upward. Key D, p. 103. 



Key A. No dorsal adipose fin; no photophores on sides of head or body. 



I a. Rays in posterior half of dorsal and in rearmost part of anal much longer than 



those in anterior part of these fins. Macristiidae.** 



I b. Not more than one dorsal ray (if any) and no anal ray much longer than the others. 



2 a. Bony (gular) plate present in chin region between branches of lower jaw. 



Elopidae, Part 3, p. iii. 

 2 b. No bony (gular) plate in chin region. 



3 a. Upper jaw reaching rearward far beyond eye. 

 4 a. Snout overhanging mouth noticeably. 



Engraulidae (western Atlantic saltwater species), Part 3, p. 152. 

 4 b. Snout not overhanging mouth. 



5a. Pectoral fin longer than head; either uppermost pectoral rays 

 or outermost pelvic rays much longer than the others; lower lobe of 

 caudal much longer than upper in some. 



Bathypteroidae in part. Part 5.^^ 



5b. Pectoral fin shorter than head; none of pectoral or pelvic rays 



prolonged; lower lobe of caudal little, if any, longer than upper. 



6 a. A fleshy ridge present along back anterior to dorsal fin. 



Alepocephalidae in part 

 {Anomalopterus), Part 3, p. 250.^* 

 6 b. No fleshy ridge on back anterior to dorsal fin. 



33. For larval stages of a few, see Key D, i b. In this key no attempt is made to present the author's views as to phylo- 

 genetic relationship. 



34. Occur in the vicinity of the Azores, hence may be taken sometime in the western Atlantic. 



35. See Key B, 4a for those with adipose fin. 36. See also Key A, iia; Key C, 15a. 



