FISHES—SCOMBRIDAE-TRACHURUS BOOPS. 
109 
and subtruncated, 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 flanks, 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, 
peptorals, and ventrals exhibit nearly the same tint as the regions where they are inserted. 
List of specimens. 
Catal. 
No. of 
Sex and 
Locality. 
When collected 
Whence obtained. 
Nature of specimens. 
No. 
spec. 
age. 
G89 
i 
Adult.. 
San Diego, Cal_ 
1857 
A. Cassidy_ 
Alcoholic_ 
