46 



U. S. p. R. R. EXP. AND SURVEYS — ZOOLOGY GENERAL REPORT. 



The branchiostegals are seven in number. The base of the dorsals is scaleless ; that of the 

 caudal and pectorals exhibit, as usual, small scales. The upper lateral line does not extend 

 beyond the middle of the spinous portion of the dorsal; the fourth is lost about the anal region; 

 the divergence of the fifth takes place somewhat nearer the origin of the ventrals than the vent. 

 The scales, at large, are of moderate development. 



The upper region of the head and body is almost black ; the lower portions of the flanks are 

 clouded with black, upon an olivaceous ground. The inferior region of the head and body is 

 olivaceous, punctated with black. The fins are olivaceous, maculated with black, the maculae 

 upon the anal fin being fewer and much larger than upon the dorsals. 



List of specimens. 



OPLOPOMA, Girard. 



Gen. CnAK. — Body elongated. Membranous flaps above the orbits ; preopercle spinous ; snout conical ; mouth large ; 

 lower jaw longest. Canine teeth upon the premaxillaries, dentaries, front of vomer, and the palatines. Gill openings 

 continuous ; branchiostegals, six on cither side. Dorsal fins continuous. Caudal posteriorly sub-crescentic or else concave. 

 Insertion of ventrals a little posterior to the pectorals. Body covered with small, cycloid scales. 



RYS.—Oplopoma, Grd. Proc. Acad. Nat. Sc. Philda. VIII, 1856, 135. 



With the general aspect of Cliirus and Chiropsis, in the shape of the body, cut of the fins, 

 and the presence of a supraocular flap ; this genus is related to Opliiodon by the shape of the 

 head, the presence of one lateral line only, and the structure of the scales, which are of the 

 cycloid type. Indeed, there is a closer aflinity between Oplopoma and Ophiodon than between 

 the other members of the same group. The i^ectoral fins resemble those of Chiropsis more than 

 those of Ophiodon. 



OPLOPOMA PANTHERINA, Grd. 

 Plate XVIII, Figs. 1—3. 



Spec. Chaii. — Body elongated and tapering. Upper surface and sides of head granular. Preoperculnr spines few, small 

 and blunt. Posterior extremity of maxillary extending beyond the orbit. Origin of anterior dorsal fin situated in advance 

 of the convexity of the preopercle. Scales extending over the base of both the caudal and pectoral fins. Blackish brown 

 above, reddish brown beneath. Dorsal and lateral regions spotted with black. 



gyN. — Oplopoma pantlierina, Grd. Proc. Acad. Nat. 8c. I'hilad. VIII, 1S56, 135. 



The body is very elongated, deepest anteriorly, and tapering gradually from the thoracic 



region backwards. It is compressed, much deeper than broad tliroughout its entire length ; 



■ its profile is sub-fusiform. The head, which constitutes a little more than the fourth of the total 



length, is elongated and conical, slightly depressed ui)on the occipital region and between the 



orbits, sloping rapidly towards the snout. A foliated membranous appendage is to be observed 



