150 HISTORY OF THE FISHES OF MASSACHUSETTS. 



Description. The surface of the body is smooth. The length of the head from the 

 posterior edge of the operculum to the angle of the jaws equal to one twelfth the entire 

 length of the fish. The length of the lower jaw, from the angle to the chin, equal to one 

 ninth the length of the fish. The length of the sword, from the anterior angle of the eye 

 to its extremity, equal to one third the length of the fish. Upper part of the sword dark 

 brown, almost black, with a groove extending throughout its whole extent. Under 

 portion of the sword lighter colored, and having a velvety feel. The edges of the 

 sword have a bony, shining, perfectly smooth edge. The widest portion of the upper 

 jaw equal to about one twelfth the length of the sword. This upper jaw gradually 

 terminates to a point. Jaws, without teeth ; a velvety feel, to the finger, upon the lower 

 jaw. Eyes large and very movable in their orbits ; the orbit horizontally oval, the eye 

 itself circular. Branchiae composed of four pairs of large parallel laminae, and one smaller 

 one. Branchial membrane composed of eight rays. 



The dorsal fin commences nearly on a line above the posterior edge of the operculum. 

 It is strongly falciform, four times as high as the upper jaw is wide ; its length is equal to 

 three fourths its height. In the specimen described in my Report, eighteen rays were 

 obvious in the anterior portion of the dorsal ; in the specimen from which my present 

 description is written, twenty-one rays may be counted, although the former specimen 

 measured twelve feet five inches, while the present one measures only seven feet three 

 inches. In this specimen, as well as that, the whole dorsal ridge between these rays, and 

 within a few inches of the base of the tail, has no vestige of a ray above the surface, 

 but in their place is a shallow groove throughout the whole extent, supporting a slight 

 membrane ; the bases of a few rays are seen, however, upon dissection, beneath the skin. 

 A few inches in front of the base of the tail is situated the extremity of the dorsal fin, 

 composed of three rays in both of the specimens I have seen, slightly emarginated above 

 and terminating posteriorly in a point, and looking like the adipose fin of the Salmonides, 

 or the finlets of many of the Scomberoides. 



The pectoral fins are also falciform, less high than the dorsal ; their length a little more 

 than one fourth the height. 



The anal fin is formed like the dorsal, and is three fifths its height. The extremity of 

 this fin terminates on the same plane with the dorsal, and is formed much like that. This 

 portion in the former specimen contained three rays, in the present two. This small 

 posterior portion is one eighth the height of the longest rays. At the base of the tail is 

 situated a transverse furrow. On each side of the base of the tail is situated a carina 

 about the height of the posterior extremity of the dorsal fin, and about as long again as 

 high, extending on to the caudal fin. 



