112 



SCANDINAVIAN FISHKS. 



The fii'st dorsal fin, all the rays of Avhicli are uii- 

 branched, is short, high and almost triangular, with 

 the upper posterior margin concave. Wlien depressed, 

 it lies hidden in a deep groove in the back; the second 

 ra-\- is the longest and the last rays are very short. 

 In a large specimen from the noi'th of the Sound there 

 are onlv 10 ravs in tliis fin, and the last ray is so 

 short that it scarcely reaches half-way u|) tlie fin- 

 groove. The second dorsal fin, which begins aliove 

 the vent, is lower than the first, concave at the upper 

 margin, lialf as liigh as it is long and covered -with 

 scales at the base The anal fin begins a little farther 

 back than the second dorsal, but it has the same form 

 and the same covering of scales. The finlets behind 

 the dorsal and anal fins consist of one ray, which is 

 branched repeatedly, and are generallj' bent side^vays 

 in opposite directions on the back and the lower caudal 

 edge. Thus, if the former are bent to tlie right, the 

 latter are generally bent to the left. The pectoral fins 

 are obliquely pointed and set, as is usual in the family, 

 in a depression, so that there is no unevenness at the 

 base when the fins are folded and laid back. In the axil 

 a dermal flap, which is folded or at least dentated at the 

 margin, hangs down from the outside of the postclavi- 

 cular bone. The ventral fins are inserted a little farther 

 forward than the beginning of tije first dorsal, and al- 

 most vertically below the beginning of the tliird fifth of 

 the length of the pectoral fins. They are narrow and 

 obliquely pointed, are set close together and, like the 

 pectoral fins, when folded, lie in a depression which 

 has a dermal fold at the sides. The caudal fin is 

 deeply forked, with narrow lobes, which are widely 

 spread and have rounded points: the number of the 

 rays, which it is difficult to distinguish on account of 

 the thickness of the fin-membrane, is about 8-|-l(]-|-8. 

 Though there is not the least external trace of a middle 

 carina on the sides of the tail, we find a raised, bony 

 ridge on the penultimate and the last caudal vertebra;. 



The colouring is so brilliant and variable that it 

 is difficult to describe. The back and the forehead are 

 dark green, with crooked, black transverse bands, some- 

 times like fine streaks (var. scriptus) and sometimes 

 broken up into spots (var. pimctatus), which extend 

 down the sides somewhat below the lateral line"; be- 

 tween these lines the colDur is a- bright bluish, shading 



into greenish yellow. At the end of the dark trans- 

 verse bands a more or less distinct, straight, black 

 streak, which is sometimes broken up into spots, runs 

 along tlie sides. From this point downward the co- 

 louring becomes gold, silver and mother-of-pearl, shad- 

 ing into red and yellow, while the belly is white. The 

 sides of the head silvery: the mai-gin of the mouth, 

 the snout, the tip of the lower jaw, the inside of the 

 branchiostegal membrane and sometimes the articula- 

 tions of the gill-cover black: the first dorsal fin a clear, 

 transi)arent gray. The second dorsal and the dorsal 

 finlets blackish gray. The pectoral fins black at the 

 base, especially on the inside, and gray at the point. 

 The ventral and anal fins and the inferior caudal edge 

 with its finlets white. The ('audal tin dark gray. 



On examination of the internal organs we find 

 that the long digestive canal consists of a wide oeso- 

 phagus, running in a straight line -with the stomach, 

 which is jjointed and extends to the region of the vent. 

 Around the pylorus and duodenum are a large number 

 of long, narrow pyloric appendages, which follo^v the 

 intestine to its first bend, from which point its dia- 

 meter varies very slightly, though it forms two more 

 bends. ( )n the interior of the stomach are a large 

 number of longitudinal folds, joined by fine, ti-ansverse 

 wrinkles. The liver, which is situated far forw^ard and 

 for the most part to the left side, consists of one, large, 

 thick lobe, which has an elongated point at its extre- 

 mity. It is pale red in colour. The gall-bladder, which 

 is long and narrow, lies on the right of the dio'estive 

 canal. The spleen is small, oblong and blackish brown. 

 The kidneys, which are narrower behind than in front, 

 are almost as long as the abdominal cavity. No air- 

 bladder. Two ovaries, as long as the whole abdominal 

 cavity. The eggs fairly small. The milt-sacs of the 

 same form as the ovaries. Malm has described herma- 

 phrodites of this species'. All the statements as to ati 

 external difference of sex in the Mackerel which have 

 been made up to the present, have proved untrust- 

 worthy on closer examination. 



The usual length of the Mackerel is between 3 and 

 4 dcni. Off the English coast'', however, specimens 

 have been found, though seldom, 470 mm. in length; 

 and AnTEDi, as well as Strom, mentions specimens, 

 the length of which was 594 ram. The species occurs 



" The colour uf the back may soinetiuu's be an unvaried bhuiv (Cdi.LETT: N. Mag. Naturv. 1884, p. 58). 

 * Ofvers. Vet.-Akad. fiirli. 1876, No. 5, p. 71, tab. V. 

 ' Day, 1. c., p. 91. 



