162 HISTORY OF THE FISHES OF MASSACHUSETTS. 



pelvis forming, anterior to the anus, a small, pointed, and cutting blade, which resembles 

 a vestige of the ventral fins. A horizontal, partially concealed spine before the dorsal 

 and anal fins. 



RHOMBUS TRIACANTHUS, Dekay. 



The Skipjack. 

 (PLATE XV. FIG. 4.) 



Stromateus triacanthus, PECK, Mem. Amer. Acad., II. p. 48, pi. 2, fig. 2.. 



Stromateus cryptosus, Cryptous Broad-Shiner, MITCH., Trans. Lit. and Phil. Soc. of N. Y., I. p. 365, pi. I, fig. 3. 



Peprilus cryptosus, Cuv., Griffith's Transl., X. p. 203. 



Le Rhombe tlfossettes (RJiombus cryptosus, NOB., Stromateus cryptosus, MITCH.), CUT. et VAL., IX. p. 408. 



Peprilus triacanthus, Three-spined Peprilus, STOKER, Report, p. 60. 



Rhombus triacanthus, Shart-finned Harvest-fish, DEKAY, Eeport, p. 137, pi. 75, fig. 80. 



" " STOKEB, Mem. Amer. Acad., New Series, n. p. 362. 



" " " Synopsis, p. 110. 



Color. Of a leaden color upon the back ; lighter upon the sides ; silvery beneath. 

 The cheeks, intermaxillaries, chin, base of pectorals, and base of caudal fin, together with 

 more or less of the abdomen, sprinkled with very minute -black dots. The opercles are 

 cupreous. 



Description. The body is ovate, very much compressed laterally, particularly at the 

 abdomen. The arch of the back is continued to the spine at the origin of the dorsal fin. 

 The length of the head is rather more than one fifth the length of the body, and is grad- 

 ually arched from the snout. The eyes are circular ; their diameter is equal to one fourth 

 the length of the head. The nostrils are small ; the anterior is circular, the posterior a 

 vertical fissure. The mouth is of moderate size. The jaws are of equal length, and 

 present at their edges a large number of very minute, equal, compact teeth. 



The lateral line, which is very well marked, commences just back of the posterior angle 

 of the operculum, and, arching backwards, curves with the back to the base of the caudal 

 fin. A slightly depressed straight line, destitute of scales, is seen passing from beneath 

 the origin of the lateral line to the middle of the fleshy portion of the tail ; and another 

 line, similar in appearance to the last, though not so obvious, passes from the inferior base 

 of the pectorals, curving with the abdomen, to the lower part of the fleshy portion of the 

 tail, corresponding in its course to that of the lateral line. These lines gradually disap- 

 pear after death. On each side of the dorsal fin, commencing at its origin and terminat- 

 ing towards its posterior half, are situated between twenty and thirty small circular black 

 punctures, the orifices of mucous ducts. 



At the origin of the dorsal fin is a small, naked, horizontal spine, pointing forwards. 

 The dorsal fin commences opposite the anterior half of the pectorals, and is continued to 

 the fleshy portion of the tail. The fifth, sixth, and seventh rays are the highest. The 



