THE SHORE FISHES OF PERU 203 



pseudobranchiae generally large, occasionally lost with age; lateral 

 line usually with an arch anteriorly, the straight part generally, and 

 the curved section rarely, armed with bony scutes; scales small, 

 sometimes embedded, and occasionally obsolete; anal fin similar to 

 second dorsal, sometimes much shorter, preceded by two strong spines, 

 generally separate and free or rarely obsolete in adults; ventral fins 

 thoracic, with I, 5 rays. 



KEY TO THE GENERA 



a. Dorsal and anal each followed by nearly or fully detached finlet; body quite 

 elongate, its depth generally less than a fourth of its length. 

 b. Straight part of lateral line with bony scutes; finlet of dorsal and of anal 



rather remote from fins; pectoral short Decapterus (p. 204) 



bb. Lateral line throughout with prominent bony scutes; finlet of dorsal and of 

 anal close behind the fins or more or less attached by membrane; pectoral 



long and falcate in adults Trachurus (p. 205) 



aa. Dorsal and anal without finlets; body variously shaped, generally deeper, 

 c. Body more or less elongate (sometimes ovate in Trachinotus) ; depth 

 usually less than half the length; forehead not extremely steep, its 

 outline continuous with curve of back, not forming an angle. 

 d. Premaxillaries protractile; ventral fin not attached to abdomen by 

 membrane; lateral line with or without bony scutes. 

 e. Anal and second dorsal of nearly equal length; pectoral long and 

 falcate in adults, except in Trachinotus. 

 f. Back notably elevated; dorsal outline generally more strongly 

 convex than ventral outline; mouth horizontal to little oblique. 

 g. Body moderately elongate; straight part of lateral line, pos- 

 teriorly at least, with bony scutes; maxillary moderately broad 

 to very broad, with a distinct supplemental bone. 

 h. Teeth in jaws uneven, in one or a few rows, usually present 

 on vomer, palatines, and tongue; second dorsal and anal 

 more or less elevated anteriorly, without a conspicuous 



sheath at base Caranx (p. 208) 



hh. Teeth in jaws in a single, even, close-set row, none on vomer, 

 palatines, and tongue; second dorsal and anal with a broad 



conspicuous sheath at base Hemicaranx (p. 211) 



gg. Body quite deep; no bony scutes in lateral line; maxillary very 

 narrow, without a distinct supplemental bone. 



Trachinotus (p. 213) 



//. Back scarcely elevated; dorsal outline much less strongly convex 



than ventral outline; mouth nearly vertical; pectoral long, 



falcate Chloroscombnis (p. 216) 



ee. Anal much shorter than second dorsal; no bony scutes in lateral line; 



pectoral short Seriola (p. 218) 



dd. Premaxillaries not protractile; ventral more or less attached to abdomen 

 by membrane; no bony scutes in lateral line. 

 i. First dorsal with 7 or 8 spines; anal much shorter than second 

 dorsal; no teeth on vomer, palatines, or tongue, those on jaws in a 



single series Neptomenus (p. 220) 



w. First dorsal with 3 to 5 spines; anal and second dorsal about equal in 

 length; teeth present on vomer, palatines, and tongue, those on 

 jaws in bands Oligoplites (p. 221) 



