312 U S P. R. B EXP. AVD SUEVEYS ZOOLOGY GENERAL REPORT. 



3. FAKIO ARGYREUS, Grd. 

 PLATE LXX. 



SPEC. CHAR. Body very much compressed, rather deep upon its middle region, and quite tapering posteriorly. Head 

 moderate, constituting the fifth of the entire length. Jaws equal. Maxillary slightly curved ; its free extremity extending to 

 a vertical line drawn posteriorly to the orbit. Anterior margin of dorsal fin nearer the extremity of the snout than the insertion 

 of the caudal fin. Bluish grey above ; silvery along the middle of the flanks ; yellowish beneath. 



Srs.Fario argyreus, GRD. in Proc. Acad. Nat. Sc. Philad. Vill, 1856, 218. 

 Salmo argyreus, GRD. Ms. 



The specimens before us are about ten inches in total length. The body is very much 

 compressed or flattened laterally, with its outline sub-fusiform, tapering considerably towards 

 the tail. The head is compressed also, otherwise it would be sub-conical, since the snout is 

 obtusely rounded and both jaws equal. The mouth is silghtly oblique and but moderately cleft; 

 the posterior free extremity of the maxillary extending to a vertical line drawn at a short distance 

 behind the orbit. The teeth are very weak and inconspicuous. The longitudinal diameter 

 of the eye is contained five times in the length of the sides of the head ; about once and a third 

 in advance of the anterior rim of the orbit. The sub-opercle is very much developed, quite 

 oblique in its position, and considerably overlapped by the opercle. There are fifteen 

 branchiostegals on the left side and fourteen on the right, short and flattened. 



The fins are moderately developed ; the caudal is deeply furcated and constitutes about the 

 sixth of the total length. The dorsal is higher than long, and its posterior margin less than 

 half the height of the anterior ; its first two rays are but rudiments, and the anterior margin 

 of that fin is nearer the extremity of the snout than the insertion of the caudal fin. The 

 adipose is very slender, opposite the posterior portion of the anal and extends a little beyond 

 the latter. The anal is longer than deep, its depth, moreover, diminishing rapidly backwards ; 

 its external margin being sub-concave. The insertion of the ventrals takes place opposite to 

 the fourth developed ray of the dorsal or the sixth in the series. The pectorals are slender 

 and their rays bifurcated also. The rays of the other fins are similarly bifurcated or branched, 

 and in the caudal usually more so than elsewhere. 



Br. 15 : U ; D 12 ; ; A 17 ; 5, 1, 9, 8, 1, 6 ; V 10 ; P 15. 



The scales are of moderate development, elongated, more or less irregular in their outlines ; 

 the concentric stria either becoming obsolete or else disappearing entirely upon their posterior 

 extremity. The lateral line takes a straight course from the upper portion of the opercular 

 apparatus to the base of the caudal fin, being nearer to the dorsal than the abdominal outline, 

 until it reaches the peduncle of the tail where it becomes absolutely median. 



The dorsal region is bluish or purplish grey, with a metallic lustre ; the middle of the flanks 

 are silvery white, or, perhaps, of a quicksilver hue ; whilst the belly is yellowish, with a 

 metallic lustre also. The upper region of the head is blackish or bluish black ; its sides and 

 the opercles being gold &quot;and silver. The fins are unicolor ; the dorsal and caudal greyish olive 

 and darker than the anal, ventrals, and pectorals, which are greyish yellow. 



The specimens from which our plate is drawn was collected at (Jape Flattery, W. T., by Lt. 

 W. P. Trowbridge. Another was obtained at Fort Steilacoom, Puget s Sound, W. T., by Dr. 

 George Suckley. 



References to the figures. Plate LXX, fig. 1, represents Fario argyreus, size of life. Fig. 2 

 exhibits a scale from the dorsal region, midway between the lateral line and the dorsal fin. 



