50 



U. S. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



extremities of these fins 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 17. 



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 back 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 be 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 back 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 back. 

 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. 



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 well deserving the name of 

 &quot; sculpins,&quot; 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 



