FISHES — SCOMBRIDAE — TRACHUEUS BOOPS. 



109 



and sub truncated, its upper angle corresponding to a vertical line which would intersect the 

 anterior rim of the pupil. The eye itself is well developed sub-circular, its longitudinal 

 diameter entering about five times in the length of the side of the head. 



The first dorsal is sub-triangular, and nearly as high as the second ; it is preceded anteriorly 

 by a small spine ; the third and fourth rays are the highest, the fifth being a good deal shorter 

 than the first (properly so called), and the sixth and seventh the shortest and more widely 

 apart than the rest. This fin, therefore, is composed of eight rays, if the anterior spine may 

 be counted as one. The anal spines are sub-equal, equi-distant between the anterior margin of 

 the anal fin and the vent, and situated opposite the anterior margin of the second dorsal ; the 

 vent itself being equi-distant between these same anal spines and the tips of the ventral fins. 

 The caudal fin is slender and very deeply forked ; the peduncle of the tail being broader than 

 deep, owing to the prominence of the lateral keel upon that region. The ventral fins are rather 

 short, and inserted upon a vertical line passing somewhat in advance of the postero-inferior 

 edge of the base of the pectorals. The pectorals themselves are falciform, broad at their base, 

 elongated and slender towards their extremity, which extends posteriorly to a vertical line 

 drawn beyond the middle of the triangular portion of the anal fin. 



Br. VII : VII ; D VIII, 24 ; A II, 21 ; C 5, 1, 8, 8, 1,5; V 1,-5 ; P 1, 24. 



The scales are of moderate development, deeper than long, sub-ellipsoid in shape, existing on 

 the upper part of the opercular apparatus as well as on the cheek. The lateral line, from the 

 upper part of the gill aperture, takes a straight and somewhat upward course until opposite 

 the base of the first dorsal fin, where an open and regular curve brings it down to the middle 

 of the fianks, hence extending straightway to the base of the fin. The armature, peculiar to 

 this genus, commences immediately below the curve just alluded to, opposite the anterior margin 

 of the second dorsal fin ; the scutellae increasing gradually in size backwards as well as the 

 spinous keel observed upon their middle region. 



The upper surface of the head and body from the lateral line upwards is greyish olive, 

 somewhat darker on the former region, whilst the flanks and the abdomen are yellowish, with 

 a metallic reflect. The posterior margin of the opercle exhibits a conspicuous black patch. 

 The dorsal and caudal fins are of a darker hue than the dorsal region, whilst the anal, 

 pectorals, and ventrals exhibit nearly the same tint as the regions where they are inserted. 



List of specimens. 



