108 
U. S P. E. E. EXP. AND SUEVEYS—ZOOLOGY—GENEEAL EEPOET. 
the total length, in which the caudal fin itself enters about five times and a half The gape of 
the mouth is oblique upwards, the lower jaw being the longest, and the posterior extremity of 
the maxillary, which is quite dilated, extending to a vertical line drawn in advance of the orbit. 
The origin of the anterior dorsal fin takes place posteriorly to the insertion of the ventrals, 
and is somewhat higher than the second. The origin of the anal is situated a little posterior to 
that of the second dorsal, and terminates almost evenly with the latter. The terminal ray of 
both of these fins, though united to them, resembles more an isolated finlet than an ordinary 
ray. It is larger than those preceding it, and hence quite conspicuous ; its tip reaches the 
rudimentary rays of the caudal above as well as below. The caudal fin is deeply furcated. 
Br. VII: VII; D VIII, 40;? A II, 1, 28; C 6, 1, 9, 8, 1, 6; Vi, 5; P 1, 22. 
The scales of the body are not preserved upon our specimens ; a few scattered ones exhibit a 
pectinated or rather spiny posterior edge, numerous and fine concentric striae, but no radiating 
furrows. The lateral line, from the upper edge of the opercle, extends nearly parallel with the 
back to the beginning of the second dorsal, where a gracefully open curve brings it along the 
middle of the tail, hence runs straightway to the caudal. The scale-like scutellae of which it is 
composed are vertically elongated and quite narrow, largest upon the middle of the tail and 
smallest upon the bent, except near the base of the caudal, where they taper off into exiguous 
plates. Their middle region is keeled, inconspicuously anteriorly, prominently along the tail, 
the keel increasing towards the caudal fin. 
The specimen before us being somewhat discolored, we have nothing to add touching its 
various tints, having quoted in the specific diagnosis the coloration as observed by Dr. Ayres 
on a fresher specimen. 
List of specimens. 
Catal. 
No. 
No. of 
spec. 
Sex and 
age. 
Locality. 
When collected 
Whence obtained. 
Orig. 
No. 
Nature of speci¬ 
mens. 
488 
i 
Young. 
San Francisco, Cal.. 
1856 
Dr. W. 0. Ayres_ 
26 
Alcoholic_ 
2. TRACHURUS BOOPS, Grd. 
Spec. Chap. —Head contained a little over four times and a half in the total length. Posterior extremity of maxillary 
extending to a vertical line intersecting the anterior rim of the pupil. Curve of lateral line situated in advance of the second 
dorsal fin. Pectoral fins very long, slender, and falcate. Greyish olive above; yellowish beneath. A black patch at the 
posterior edge of the opercle. Fins unicolor. 
As the specimen upon which this species is established may be considered of mature growth, 
its characters will better compare with those of the preceding one, and especially with the 
description of the latter by Dr. Ayres. 
Its total length measures twelve inches, the head being contained in it a little over four times 
ai d a half, and exactly four times to the fork of the caudal fin. The body is elongated, very 
much compressed, subfusiform in its profile, and of great symmetrical beauty. The greatest 
depth which corresponds to the origin of the second dorsal enters about four times in the total 
length. The upper surface of the head is sub-convex, and gently declivous forwards, the snout 
being rounded and rather obtuse, the lower jaw projecting slightly beyond the upper, owing to 
the obliquity upwards of the gape of the mouth. The maxiilar bone is quite dilated posteriorly 
