68 



ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 



I have termed this species signata, in reference to the black patch on the 

 opercle, which is a conspicuous character. The only specimen in the collection 

 was obtained by Mr. Darwin at Bahia Blanca, on the coast of North Patagonia. 



1. Caranx declivis. Jen. 

 Plate XIV. 



C. corpore elongato, altitudine quintam, capite quartam partem longitudinis cequante; 

 maxilla inferiore longiore ; lined laterali infra quintum radium dorsalis sectmdce 

 subito declivi, per totam longitudinem armatd, laminis 82 altioribus quam longis, 

 ubique cequalibus ; spind reclinatd ante pinnam dorsalem parvd, mucrone tamen 

 nudato ; pectoralibus ultra pinnulam analem, et prope ad analem ipsam, pertin- 

 gentibus. 



B. 7 ; D. 8—1/35 ; A. 2—1/30 ; C. 17, &c. ; P. 21 ; V. 1/5. 

 Long. unc. 7. lin. 10. 

 Fohm.— Rather more elongated than the C. trachurus of the British seas. Greatest depth one-fifth 

 of the entire length: head one-fourth of the same : thickness about half the depth. Diameter 

 of the eyes a little less than one-third the length of the head. Lateral line bending downwards 

 more suddenly, and at a more backward point than in that species. The bend commences in 

 a line with the fifth ray of the second dorsal, and is entirely comprised within a space equal to 

 that occupied by four fin rays,* so that opposite the ninth ray it again advances in a horizontal 

 line. The posterior portion about equals in length the anterior, the bend being included in this 

 last. The laminae which protect the lateral line, and which extend throughout its whole 

 length, are well developed, and everywhere of the same breadth ; this breadth equalling nearly, 

 but not quite, one-third the depth of the body. In number they are eighty-one or eighty-two ; 

 of which the last thirty-eight or forty, forming the posterior portion of the line, have keels 

 terminating backwards in sharp spines : these spines are at first small and inconspicuous, but 

 gradually increase in size as they advance towards the thinnest part of the tail, where they are 

 sharpest and most developed. 



In most of its other characters this species so closely resembles the C. trachurus, as to 

 render a detailed description unnecessary. The reclined spine before the first dorsal, however 

 is smaller, though the point is sharp and exposed : also the number of rays in the second 

 dorsal and anal is greater by five in each fin. The length of the second dorsal is two-and-a- 

 half times that of the first. The pectorals are long, narrow, and pointed ; a little shorter than 

 the head, or rather less than one-fourth of the entire length ; when laid back, they reach 

 beyond the anal finlet, and very nearly to the commencement of the true anal itself. 

 Colour. — Not noticed in the recent state. So far as can be judged from a specimen in spirits, the 

 colours appear to have been similar to those of the C. trachurus ; and there is the same black 

 spot on the upper part of the opercle. 



* In the C. trachurus, the bend begins in a line with the commencement of the second dorsal, and from its 

 more gradual obliquity, extends over a space equal to that occupied by nine fin-rays. 



