75. CARANGID.E TRACHURUS. 431 



behind the last. Gill- rakers usually long. Branchiostegals commonly 

 7. Air-bladder present, often bifurcate behind. Pseudobranchirc large, 

 present in all our genera, sometimes disappearing with age. (Esopha- 

 gus unarmed. Pyloric cceca generally numerous. Vertebra?- fewer than 

 in the Scombridcv, about 25 in number. Coloration generally metallic 

 and silvery. Genera 25; species about 180, abounding in warm seas, 

 often moving northward in summer, like the Scombridce. Most of the 

 species are widely distributed, and nearly all are valued as food. 



(Carangidw pt. Gunther ii, 417-485, exclusive of certain genera.) 



* Lateral line armed with bony keeled plates, at least posteriorly. (Carangince.') 



a. Armature of lateral line extending its whole length TRACHURUS, 219. 



aa. Armature of lateral line on its straight posterior portion only. 



b. Dorsals and anal each with a detached finlet DECAPTERUS, 220. 



bb. Dorsal and anal without fiulets. 



c. Spinous dorsal developed CARANX, 221. 



cc. Spiuous dorsal rudimentary or disappearing with age ; scales rudimentary. 



BLEPHARIS, 222. 



*" Lateral line Tinarmed. 



d. Premaxillarics protractile. 

 e. Anal fin about equal to the soft dorsal, its base longer than the abdomen ; 



tail not keeled. 

 /. Thoracic region treuchant ; body excessively compressed. 



y. Dorsal outline more convex than the ventral outline ; profile very steep; 

 head very short and high; preorbital very deep. (Selenitic?,.) 



SELENE, 223. 

 gg. Dorsal outline less convex than ventral ; profile not steep ; preorbital 



moderate. ( 67i loroscom brinoc. ) CHLOROSCOMBRUS, 224. 



ff. Thoracic region not trenchant; body moderately compressed. (Tra- 

 cliynotinoR.) 



Ji. Forehead convex TRACH YNOTUS, 225. 



ee. Anal fin much shorter than the soft dorsal, its base not longer than the 



abdomen; tail keeled. (Svriolincu.) 

 i. Fiulets none. 



j. Dorsal spines free, in adult NAUCRATES, 226. 



jj. Dorsal spines connected by membrane SERIOLA, 227. 



ii. A two-rayed fiulet behind dorsal and anal ELAGATIS, 228. 



del. Premaxill aries not protractile ; dorsal and anal with finlets ; maxillary 

 very narrow, without distinct supplemental bone. (Scombroi- 

 dlnce.) SCOMBROIDES, 229. 



219. TRACHURUS Rafinesque. 

 Saureh. 



(Rafinesqne, Indiced'Ittiologia Siciliaua 1810, 20 : type Scomber trachurus L. = Tracliurus 

 saurus Raf.) 



Body rather elongate, somewhat compressed, not elevated, taperiug 

 to a slender caudal peduncle, which is as broad as deep. Scales present, 

 not very small. Lateral line armed throughout with plates, those on the 

 caudal peduncle larger and spinous; an accessory dorsal branch to the 

 lateral line. Snout rather long. Mouth moderate. Minute teeth mostly 



