FISH. 67 



though at the upper portion there are two small blunt points distinguishable by the finger, 

 between which there is a very shallow notch : the line of separation between these two bones 

 descends obliquely forwards to a little above the rounded angle of the preopercle, where it meets 

 the line of the interopercle, which descends obliquely backwards:* all the margins of the oper- 

 cular pieces entire. Gill opening very large, the aperture reaching to beneath the anterior mar- 

 gin of the eye : the membranes, each of which has as many as ten rays,f cross a little over each 

 other, and are not united to the isthmus. 



Snout, jaws, and cheeks, as well as the several pieces of the gill-cover, without scales : % 

 body covered with extremely minute ones, of an oval form, longer than broad, marked with con- 

 centric circles, and entire on the margin. The lateral line is slightly arched above the pectoral, 

 and its course a little undulating, but it descends gradually to near the middle of the body, 

 whence it runs straight to the caudal. 



The first dorsal is represented by five short free spines, each capable of separate motion, 

 and each furnished with its own membrane ; in advance of them is a somewhat smaller reclined 

 spine with its point directed forwards : the first erect spine is above the middle of the pectoral, 

 and distant from the end of the snout nearly one-third of the entire length. Beyond the five 

 free spines, and immediately before the commencement of the second dorsal is another small spine 

 closely pressed down, and almost concealed beneath the skin, pointing backwards. The second 

 dorsal, which has also at its anterior edge a small spine one-third the length of the first soft ray, 

 commences at the middle point of the entire length, caudal excluded. The general form of this fin 

 is similar to that of the genus Lichia, long, with the anterior portion elevated; the greatest height 

 about one-fourth of the depth, or hardly so much. The anal answers exactly to the second 

 dorsal in form and extent, and is preceded by two free spines, separated from it by a small space, 

 besides a longer one at its anterior edge. Caudal forked nearly to the base, where there are a 

 number of minute scales ; the lobes equal, pointed, and moderately elongated, each contained 

 about four times and one-third in the entire length. Pectorals attached at about the middle 

 of the depth, a little behind the opercle ; of a somewhat triangular form, small, their length not 

 much exceeding half that of the head. No trace of ventrals whatever. 

 Colour. — " Uniform bright silvery, the ridge of the back bluish : a black patch on the gill-cover, 

 and another under the pectoral fin." — D. — The first of the patches alluded to by Mr. Darwin 

 is very conspicuous, and is situate at the upper angle of the opercle, immediately in advance of 

 the commencement of the lateral line. The second may be described as consisting of two dis- 

 tinct spots ; one at the root of the upper rays, and completely in the axilla ; the other, a small 

 one of an elongated form, immediately beneath the lowest ray, and partly visible without raising 

 the fin. The elevated portion of the second dorsal is also dusky, and a faint edging of this 

 colour runs for a short way along the margin of this fin. The anal is pale. 

 Habitat, Northern coast of Patagonia. 



* This part is exactly as described by Cuvier and Valenciennes in the Lichia Amia, to which genus the 

 present one is so nearly allied. 



+ Ltekia Amia is represented as having nine; and this forms another mark of affinity between the two 

 genera. 



% There are scales on the cheeks in Lichia, according to Cuvier and Valenciennes, but I see no appearance of 

 them in this genus. 



