246 



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



2. POGONICHTHYS SYMMETRICUS, B. & G. 



Spec, Char.— Head constituting the fifth of the total length. Snout rounded and sub-conical. Gape of mouth somowliat 

 arched ; lower jaw shorter than the upper. Posterior extremity of the maxillary corresponding to a vertical line drawn behind 

 the nostrils. Anterior margin of dorsal fin nearer the insertion of the caudal than the extremity of tiio snout. Insertion of 

 ventrals placed in advance of tlie anterior margin of the dorsal, and tomcwhat nearer the insertion of the caudal than the tip of 

 the snout. Lobes of caudal fin equally developed. Dark greyish brown or blackish above ; yellowish golden beneath. 



Stn. — Pogonichtliys symmelricus, B. & G. in Proc. Acad. Nat. Sc. Philad. VII, 1854, 13G.— Ghd. in Proc. Acad. Nat. Sc. 

 Philad. VIII, 1856, 188. 



The Bpecimens before us being in a rather poor state of preservation, a description of the 

 species can hardly be drawn with accuracy. The size of the largest one is about four inches and 

 a half in total length ; the profile of the body is sub-fusiform, very much compressed, and 

 gracefully elongated. The head constitutes the fifth of the total length. The eye is large, its 

 diameter being contained less than four times in the length of the side of the head. The lobes 

 of the caudal fin are symmetrical. The anterior margin of the dorsal is equidistant between the 

 extremity of the snout and the tip of the central rays of the caudal. The lateral line forms a 

 gentle curve, convex downwards, upon the middle of the abdomen, and nearer the insertion of 

 the ventrals than the base of the dorsal. The insertion of the ventrals is situated in advance of 

 the anterior margin of the dorsal, a character which will at once enable us to distinguish this 

 species from P. inaequilohus. 



The scales are moderate, longer than deep, anteriorly sub-truncated, posteriorly rounded, 

 with radiating furrows upon their posterior section only. 



The upper regions are dark greyish or blackish brown, whilst the inferior regions are of a 

 yellowish golden tint, the upper part of the sides being mottled with yellow and the lower part 

 dotted with black. The dorsal and caudal are greyish olive ; the other fins, greyish orange. 



List of specimens. 



3. POGONICHTHYS AEGYREIOSUS, Grd. 



Si'EC. CiiAR. — Head constituting the fifth of the total length. Snout sub-conical ; gape of mouth nearly horizontal ; lower 

 jaw shorter than llio upper. Posterior oxtromity of ni.i.xillar bone reaching a vertical line drawn at the anterior rim of the orl'it. 

 Anterior margin of dorsal fin e(|uidistiint between the extremity of the snout and the insertion of the caudal. Insertion of ven- 

 trals somewhat behind the anterior margin of the dorsal, and nearer the base of the caudal than the tip of the snout. Lobes of 

 caudal fin equally developed. Rufous brown above ; silvery beneath. 



S\ii.—rogonichtliijsars>jrciosus, Gnn. in I'roc. Acad. Nat. Sc. Philad. VII, 1854, 154 ; &, VIII, I85G, 188. 



