958 



SCAXDIXAVIAN FISHES. 



(ioiially 24 — 32) from the isthmus to the ventral tins, 

 and 13 — 15 (exceptionally 11 — 20) between these fins 

 and the vent, in all 36 — 48. -hist in fi'(jnt of the ven- 

 tral lins lies a d(.)uble plate, the upward processes being 

 bifid, or showing indications that they were originally 

 comjwsed of as many as three processes. The other 

 l)reabdominal plates, on the other hand, with the ex- 

 ception of the foremost ones, are distinguished from those 

 of the following species liy their long" lateral processes. 

 The colour of the back is steel-blue with a lustre 

 of green and gold; the sides are silvery. The limit be- 

 tween the colours of the back and belly is often marked 

 l)y a tinge of lustrous green. The new-caught Herring 

 glitters \\'ith a wealth of hues, and in the darkness it 

 gleams with phosphorescent light. The snout and the 

 ujiper parts of the head, as well as the superior part of 

 the opercular margin, are sometimes pure black. The 



Fig. 240. Spiiiiferous scales from tlje ventral margin of a Clupea 



harengus 25 cm. long. Twice the natural size. 



a, tbe foremost spiniferous scale; b, (lie fifth, counting forward from 



(he ventral fins; c, the double scale just in front of the ventral fins; 



(7, (lie fifth scale, counting forward from the ven(; c. the hindmost 



spiniferous scale. 



gill-covers are of a golden lustre, more and more suf- 

 fused with blood, the longer the fish has been dead. 

 Tiie ventral and anal fins are ^vhitc Init transparent, as 

 well as the pectorals; but the ujiiier margin of the last- 

 mentioned fins is of a grayish or greenish black, which 

 colour extends, in greater or less intensity, some way 

 down the fins. The dorsal and caudal fins are darker, 

 though the membrane is transparent, more densely speck- 



led with grayish black, shading on the raj-s into green. 

 The iris is sometimes silvery with a brassj^ lustre; in 

 other cases the latter colour is predominant. 



With coloration of a lighter or darker tone, and with 

 body more or less transparent, though this transparency 

 is always faint, the Herring varies according to the 

 greater or less intensitv of light in its surroundings. 



In the temperament of the whole Herring family 

 gregariousness and a love of migration are the most pro- 

 minent traits. The common Herring, an inhabitant of 

 the North Atlantic and probabl}-, as wa have mentioned 

 above, of the corresponding regions in the Pacific, roves 

 in huge shoals ^vithin the said geographical range. How 

 far its wanderings e.xtend, is still an undecided question, 

 though numerous investigators, from the beginning of 

 the last centarv until now, have devoted their attention 

 to its solution. In an AtJas mariiimua commercialis, 

 printed in London in 1728, reference is made to the 

 annual course of the Herring-fishery off the coasts of 

 Great Britain and Ireland, then essentially the same as 

 it is to the present day. The most imijortant fishery 

 in those waters begins in summer to the extreme north, 

 off the Shetland Islands and then on the Scotch coa.st, 

 but afterwards advances further and further south on 

 both sides of Great Britain, to England, Ireland, and 

 the Channel. Hence it Avas inferred that the Herring- 

 shoals must come from the far North; they were sup- 

 posed at first to be so large and denselj' packed that 

 they had difiieultv in forcing a passage "between the 

 coasts of Greenland and North Cape"; but the Herring 

 "army" divided as it came further south. On these as- 

 sumptions the learned and clever Burgomaster of Ham- 

 burg, JoHAN Ander.sson, (1. 1743", based his theory of 

 the aiiiuial migrations of the Herring. The Herring, he 

 opined, liad its true home under the ice of the Arctic 

 Circle. There lay its ci'adle, and thither it retreated 

 year after )ear to escape its merciless pursuers, and to 

 recruit its thinned numbers. But soon the home became 

 overcrowded; large multitudes were yearly compelled to 

 emigrate southwards, and to divide into separate armies, 

 which marched partly to the right, to America, and 

 partly to the left, to the ^vest coast of Europe and into 

 the Baltic. This theory ■was still accepted in the days 

 of Pennaxt''; but Bloch'" and Noel'' showed it to be 



" See his Sachriclilni von hltinil, GnmlanJ iind der Strasse Dav 



' Brit. Zooloijn, 17 70. 



' Fisdie DeutschL, pari. 1, j). 18'j. 



'' Magazin Encyclope<liiiuc, tome VI, p. 5 (Paris 1795). 



174(3, pp. 51—72. 



