62 
U. S. P. R. R. EXP. AND SURVEYS-ZOOLOGY—GENERAL REPORT. 
LEIOCOTTUS, Girard. 
Gen. Char. —Head perfectly smooth ; spines upon the preopercle only. Mouth moderately cleft; jaws equal. Teeth upon 
the premaxillaries, dentaries, and front of vomer; none on the palatines. Barbules at the maxillaries. Gill openings con¬ 
tinuous under the throat; branchiostegal rays, five. Dorsals nearly contiguous upon their bases. Ventrals inserted backwards 
of the base of the pectorals. Caudal posteriorly subtruncated. Skin perfectly smooth, bearing neither prickles nor scales. 
Lateral line well marked, and continuous from head to tail. 
Syn. — Leiocotlm, Grd. Proc. Acad. Nat. Sci. Philad. VIII, 1856, 133. 
This genus is allied to Leptocottus, of which it has the general physiognomy. It is, however, 
distinguished from it by a smaller mouth and equal jaws ; hy the absence of teeth upon the 
palatine hones, the continuity of the gill openings, and the presence of five branchiostegals, 
instead of six. It differs from Scorpaenichthys hy a smooth head and the absence of teeth on 
the palatine hones. 
LEIOCOTTUS HIRUNDO, Grd. 
Plate XVI, Figs. 2 & 3. 
Spec. Char— Snout declivous and rather pointed; posterior extremity of maxillary provided with two or three barbules, and 
reaching a vertical line drawn a little beyond the anterior rim of the orbit. Superior regions blackish brown ; whitish under 
the abdomen, and yellow under the tail. 
Syn. — Leiocollus hirundo, Grd. Proc. Acad. Nat. Sci. Philad. VIII, 1856, 133. 
The general aspect of this species is elongated ; sub-fusiform when viewed in profile. The 
body is compressed, deeper than broad upon its whole length. The head enters about three 
times in the length of the body and caudal fin ; its upper surface is depressed, nearly flat; the 
fronto-nasal region very declivous, and the snout prominent. The mouth is but moderately cleft 
the posterior extremity of the maxillary upon which two or three thread-like barbels may be 
observed, reaches posteriorly a line which would be drawn a little inwardly of the anterior rim 
of the orbit. Teeth exist upon the premaxillaries, dentaries, and front of the vomer, whilst 
the palatine bones are smooth and toothless. The jaws are equal, and surrounded hy conspicuous 
lips. The nostrils are situated towards the upper surface of the snout, much nearer to the orbit 
than the extremity of the snout, and preceded by a small, inconspicuous spine. The eyes are 
large and sub-circular, approximating the upper surface of the scull. Their longitudinal diameter 
enters about four times in the length of the side of the head. A bifurcated spine may be 
observed upon the convexity of the preopercle, with the points turned upwards. Two smaller 
and obtuse spines exist along the inferior margin of the same hone. 
A vertical line drawn from the origin of the first dorsal fin would strike the middle of the 
base of the pectorals, and therefore a portion of the opercle also. It is composed of nine spiny 
rays, the anterior one being the highest of all the dorsal rays. The second is next in size, and 
somewhat shorter than the highest rays of the second dorsal. The remaining rays are all much 
shorter than the second dorsal, and that portion of the fin which they constitute is convex upon 
its upper margin. The membrane of the posterior ray of the first dorsal does not quite extend 
to the anterior ray of the second dorsal. The second dorsal is composed of seventeen undivided 
rays, diminishing slightly in height posteriorly. The caudal is subtruncated, composed of nine 
bifurcated rays, and two undivided, together with a few rudimentary ones above and below. 
That fin forms about the fifth of the total length. The origin of the anal is situated opposite 
