50 
U. S. P. R. R. EXP. AND SURVEYS—ZOOLOGY-GENERAL REPORT. 
extremities of these tins are nearly even with the extremities of the ventrals, leaving a distance of 
an inch and three-quarters between them and the vent. 
Br. VI: VI; D XXVI, 22 ; A 24 ; C 7, 1, 5, 6, 1, 6 ; V I, 5 ; P IV 
The scales are very small, truly cycloid in structure, elongated in shape, sub-ovoid, with their 
anterior margin undulated by the presence of a few radiating grooves. Those of the lateral line 
are smaller than those on either the hack and abdominal region ; the mucous tubes are greatly 
developed. The upper surface of the head is spread over with minute scales. The latter may 
likewise he observed along the rays of the caudal fin to nearly the half of their length. 
The ground color of the upper regions of the body and head is olivaceous brown ; there are 
irregular or sub-circular blackish spots scattered all over the hack and sides, the head and cheeks ; 
also over the dorsal and caudal fins, the ground color of which is the same as that of the hack. 
The lower region of the flanks and the belly are uniform yellowish or dull whitish. The anal 
and ventrals are generally unicolor, and sometimes yellowish at the base, and brownish or 
blackish exteriorly. The ventrals are barred transversely with dark brown or black on a 
yellowish or olivaceous ground. 
References to the figures .—Plate XVIII, fig. 4, represents Ophiodon elongatus, somewhat 
reduced in size. Fig. 5 is a scale from the dorsal region. Fig. 6, a scale from the lateral line. 
Fig. 7, a scale from the sides of the abdomen. 
List of specimens. 
Catalogue num¬ 
bers. 
No. of specimens. 
Locality. 
When collected. 
Whence obtained. 
Nature of speci¬ 
mens. 
Collected by— 
276 
2 
San Francisco, California_ 
1853 
Lieut. Williamson_ 
Alcoholic_ 
Dr. Heermann_... 
277 
2 
Humboldt bay, Cal. ...... 
1855 
Lieut. Trowbridge_ 
_do_ 
Lieut. Trowbridge... 
Family COTTIDAE? Girard. 
A trait belonging to all cottoids, properly so called, consists in the absence of true scales, and 
which we have found so diversified in the foregoing family. The skin, however, does not con¬ 
stitute a smooth and uniform covering to the head and body throughout all the members of the 
present family, and in that respect we meet with almost the same diversity of dermic produc¬ 
tions. In some genera the skin, indeed, is perfectly smooth ; in others, it is studded with 
minute prickles, either simple or compound, rendering it very rough to the touch ; others, 
again, exhibit longitudinal series of bony shields ; and, still, others are provided with parallel 
rows of small scale-like plates of various forms and structure. 
The head is always very large ; the body very thick anteriorly, and tapering rapidly 
posteriorly. Its upper surface, in most instances, exhibits spines or tuberosities. The opercular 
apparatus is likewise provided with spines, larger still, thus w r ell deserving the name of 
“ sculpins,” by which these fishes are commonly designated. 
There are two dorsal fins, sometimes contiguous upon their base, sometimes separated. The 
anterior fin is always composed of spiny rays. The anal is situated opposite the second dorsal 
