Zoology^ NATURAL HISTORY OF VICTORIA. [Fishes. 



Plate 18. 



TKACHURUS TRACHURDS (Lin. sp.). 



The Horse Mackerel. 



[Genus TRACHURUS (Cuv.). (Sub-kingd. Vertebrata. Class Pisces. Order Acanthop- 

 terygia. Fain. Carangidae.) 



Gen. Char. — Body moderately slender, compressed, fusiform, covered with small scales, 

 except on the lateral line, which is set from anterior to posterior end with a series of large 

 elliptical plates three or four times higher than long, each with a spine directed backwards near 

 the middle. First dorsal fin less than half the length of the second, of one small anterior spine 

 directed forwards, and eight slender spinous rays ; second dorsal extending nearly to base of 

 tail, of one spinous and many branched rays ; anal, as long as the second dorsal, of two very short 

 thick spines, forming a small fin in front of the remaining portion, of which the first slender 

 ray is spinous, the rest branched ; pectoral pointed ; caudal deeply forked. Teeth minute on 

 jaw, vomer, and palate bones. Branchiostegal rays seven ; pseudobranchiae ; swimming-bladder 

 forked behind.] 



Description. — Fin rays : 1st dorsal of 8 spines, the third longest ; 2nd dorsal 

 scarcely separated from the anterior ; 1st ray a slender spine, nearly twice the leDgth. 

 of the last ray of the 1st dorsal and J- the length of the first of the 32 branched rays ; 

 anal, 2 short anterior spines only J of the length of the slender one in front of the 

 series of 28 branched rays ; pectoral fin pointed, reaching to 3rd ray of 2nd dorsal, 

 of 21 rays ; ventral fin of 1 spinous and 5 branched rays ; caudal fin of 15 rays, with 

 5 short rays above and 5 below those extending to the angles of the fin. Scales : 

 along lateral line, 84 ; above, 10 ; below it, 16. Form : greatest depth of body, in 

 front of 1st dorsal, about five times in length to middle edge of caudal fin ; thickness 

 there rather more than half the depth ; section at tail rhombic, slightly wider than 

 deep; diameter of eye slightly less than length of snout; length of head equal to 

 length of pectoral, and \ of total length to middle edge of caudal fin ; lateral line at 

 about J of the depth from the dorsal edge until end of 1st dorsal, then bending down 

 and continuing about the middle of the side to the caudal. Color : back and upper 

 part of sides olive bronze - green, freckled with darker; top of snout, base of 

 pectoral, and round blotch at posterior angle of operculum brownish-black ; lower 

 part of cheeks, sides, and belly greyish- white, with brilliant iridescent reflections of 

 pink, gold, and emerald-green ; caudal fin pale-olive, with darker margin, and 

 speckled with blackish ; the other fins pale-greyish, speckled with blackish ; iris 

 golden-yellow above, silvery below. 



Reference. — Scomber trachurus (Lin.), Syst. Nat., 1, p. 494 ; Bloch, t. 56. 

 Caranx trachurus (Cuv. & Val.), Hist. Poiss., v. 9, t. 246. 

 Dec. ii. [ 25 ] D 



