48 



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



The scales are small, cycloid in structure, elongated, sub-elliptical, much longer than deep ; 

 rudimentary or very small ones may be observed upon the base of the pectorals and caudal and 

 extending to a certain distance along their rays. The upper surface of the head is scaleless, but 

 finely granular. The temporal and facial regions are also granular, whilst over the opercular 

 apparatus the skin is perfectly smooth. The lateral line is composed of a series of membranous 

 tubes. 



The ground color is blackish brown above, and reddish brown beneath. The dorsal and 

 lateral regions are scattered all over with small black spots, which maybe observed on the oper 

 cular apparatus and cheeks. The inferior regions are unicolor. 



References to the figures. Plate XVIII, fig. 1, represents Oplopoma pantherina, somewhat 

 reduced in size. Fig. 2, a dorsal scale. Fig. 3, a scale from the abdominal region. 



* f 



List of specimens. 



OPHIODON, Girard. 



GEN. CHAR. Mouth deeply cleft ; canine teeth on both jaws ; very long patches of velvet-like teeth on the vomer and 

 on the palatines. Convexity of preopercle provided with small spines. Minute scattered scales on the head, cheeks, and 

 opercular apparatus. No membranous flap above the orbit. Gill openings continuous under the throat ; isthmus, therefore, 

 absent. Branchiostegal rays six in number. Scales very small, not serrated posteriorly. Lateral line concurrent with the 

 dorsal outline. 



SYN. Ophiodon, GRD. in Proc. Acad. Nat. Sc. Philad. VII, 1854, 133. 



The body and head are more slender than in Chiropsis ; the mouth more deeply cleft and the 

 canine teeth much more developed. The velvet-like teeth constitute longer patches. There is 

 one continuous dorsal fin, the spinous portion of which is longer than the soft and articulated 

 portion, whilst in Chiropsis the spinous portion constitutes a separate fin, and is shorter or 

 equal to the soft portion. The absence of a membranous flap above the orbit and the presence 

 of small spines on the preopercle will likewise distinguish Ophiodon from Chiropsis. The scales, 

 pectinated in one and smooth in the other, will afford the means of discriminating very readily 

 between both genera. 



OPHIODON ELONGATUS, Grd. 

 PLATE XVIII, FIGS. 4-7. 



SPEC. CHAR. Body lanceolated ; head sub-conical, depressed. Mouth deeply cleft; posterior extremity of maxillary 

 extending to the vertical of the posterior rim of the orbit. Spinous portion of dorsal fin much longer than the articulated 

 one. Anal somewhat longer than soft portion of dorsal. Caudal slightly emarginated posteriorly. Extremities of the 

 pectorals nearly even with the tips of the ventrals. Color above olivaceous brown, scattered all over with blackish, 

 sub-circular spots. Beneath yellowish. 



SYN. Ophiodon elongatus, GHD. Proc. Acad. Nat. Sc. Philad. VII, 1854, 133. 



