FISHES — SCOMBRIDAE — TRACHURUS 8YMMETRICUS. 



107 



at its onset than further back. The caudal keel or ridge begins almost evenly with the ante- 

 penultimate finlets, and extends to the base of the caudal fin, being more developed upon its 

 middle than at its extremities. The accessory keels at the base of the caudal fin may easily be 

 observed, although much less developed than the one just referred to. 



The upper surface of the head, and occipital region to the first dorsal are bluish black. The 

 dorsal region is rather lighter, though bluish still, with three longitudinal and somewhat 

 oblique blackish streaks, starting from various points on the lateral line and running towards 

 the dorsal line, parallel to one another. The rest of the flanks and sides of the head are silvery, 

 whilst the abdominal region, properly so called, is yellowish golden. The dorsal and caudal 

 fins are bluish black also, the anterior dorsal being a good deal darker than the others ; the 

 pectorals are greyish above and yellowish beneath, whilst the ventrals and the anal are of a 

 pure lemon hue. 



List of specimens. 



TRACHURUS, Rafin. 



Gen. Char. — Body elongated, compressed, sub-fusiform in its profile. Head well developed, compressed also. Mouth 

 moderate ; lower jaw longest. Small teeth on the jaws ; velvet-like teeth upon the vomer and palatine bones. Opercular 

 apparatus smooth. Branchial apertures continuous under the throat. Two dorsal fins distinct. Two free spines in advance of 

 the anal fin. Caudal furcated. Scales moderate in size. Lateral line composed of narrow and vertical scutellae, keeled 

 upon their middle and acerated posteriorly. 



Syn. — Trachurus, Rafin. Caratt nuovi Generi e nuove specie di Animali, &c. della Sicilia, &c. 1810. — Cnv. & Val. Hist. 

 nat. des Poiss. IX, 1836, 6. 



Observ. — This genus may be distinguished from Caranx proper by the structure of its lateral 

 line, which is composed of vertical, scale-like scutellae throughout its whole length, whilst in 

 Caranx the same scutellae are observed upon the posterior portion of the body only. The 

 general shape of Trachurus appears to be more elongated also than in Caranx. In both, 

 however, we obseri^e a small, nearly horizontal spine, at the anterior margin of the first dorsal 

 and directed forwards. 



1. TRACHURUS SYMMETRIC US, Grd. 



Spec. Char. — Head forming the fourth of the total length. Posterior extremity of maxillary extending to the anterior rira 

 of the orbit. Scutellae of lateral line smallest upon its bent, under the anterior third of the second dorsal. " Greenish brown 

 above, lighter on the sides, silvery beneath. Sides silvery. A brownish black blotch at the superior and posterior angle of the 

 opercle. Dorsals somewhat clouded ; other fins nearly colorless." 



Stn. — Caranx symmetricus, Atres, in Proc. Cal. Acad. Nat. Sc. I, 1855, 62. 



The specimen which we describe is but five inches and a quarter in total length, whilst the 

 one first observed by Dr. Ayres measured seventeen inches, and since we have to deal with an 

 immature specimen we will briefly state a few of its most prominent features. 



The body is compressed and sub-fusiform in its profile, the head forming about the fourth of 



