84 



SCANDINAVIAN FISHES. 



often occur in shoals, wandering at the surface out at 

 sea or along the coast, they are of great importance to 

 the tishernian. Their economical value, however, is far 



less than that of the true Mackerels. Only one species 

 belongs to the Scandinavian Fauna. 



Genus CARANX. 



The lateral Ihie proper armoured, at least in part. The other scales on the loch) eijcloid. Tail keeled on the 

 sides. A spine starts, in a forirard direction from the fourth interneural hone, which supports the first spinous 



rail in the anterior dorsal fin. 



All the Carangidce furnished with scales, Avhich, 

 like the Sticklebacks, have the lateral line wholly or in 

 part covered \x\i\\ plates, — the form of \vhich strongly 

 reminds us of the high scales we have seen in the 

 iiranioids — ai'c so closely related to each other that 

 with GuNTiiER we may well unite them into one single 

 genus. The variety of form — about 80 species are 

 more or less known — may induce us, it is true, to 

 seai'ch for subdivisions within this genus. Such divi- 

 sions have been proposed, grounded partly on the dif- 

 ferent extent of the armour on the lateral line, partly 

 on the breaking-up of tlie posterior parts of the dorsal 

 and anal fins into small, separate fins which occurs in 

 some species. Both these diffei-ences, ho-wever, are met 

 with as changes due to age in forms so closely allied 

 in other respects that the assumption of a generic di- 

 stinction appears unnatural. Lutken", too, though he 

 still ado[)ted the genus Trachurus as distinct from 

 Caranx, Avrites as follows: — "At a certain age (at a 

 lengtli of 17 mm.) only the posterior half of the lateral 

 line is distinct, and one might more readily suppose 

 the young specimen before him to belong to Caranx 

 than to Trachurus." True, the same remark applies 

 to the covering of scales, which is absent in the fry; 

 but in addition to this lack of scales we find in Gall- 

 icJitJiifS so striking a development in the high form of 

 the body and so gi'eat a. reduction of the first dorsal 

 hn that we ma>- well follow LOtken and designate 

 these forms l)y a special generic name, pointing to 

 their im])(irlauce as intermediate forms between Caranx 

 and Selene. 



In Caranx the system of tiie lateral line shows so 

 higli a degree of development as to place it on a level 

 with or even above this system in Cantharus. From 

 the arcuate canal in tlie posttemporal region (above 

 the gill-c()ver and the u])per corner of the gill-opening) 



which is continued without interruption by the lateral 

 line proper, anteriorly there start two bi'anches. The 

 one as usual follows the outer edge of the preoperculum 

 do■\vn^vards and sends out its numerous lateral branches 

 with small pores in the 'adipose membrane' which 

 covers the Inroad margin of the preoperculum, and is 

 continued on the lower side of the lower jaw. The 

 other branch of the temporal canal advances towards 

 the posterior orbital margin but divides into two, the 

 one l:)eing continued forward above the eye to its 

 middle point, the other l)elonging to the suborbital 

 ring and, together with its many small branches in a 

 do\vn'ward direction, covered by the 'adipose membrane'* 

 Avhich lies over the posterior and anterior portions of 

 the eye. These small branches and pores are, as usual, 

 most distinct on the preorbital bone. From the tem- 

 poral canal there also starts the ordinary ujtAvard In'anch 

 towards the occiput, but in this case the most impor- 

 tant continuation of the latter is the dorsal canal (the 

 dorsal lateral line), Avliich runs along the base of the 

 dorsal fins, often right to the end of the posterior one. 

 From the bow which forms the connection between 

 this dorsal canal and the temporal one, there starts 

 back^vards, from the concave side of the bow, a smaller 

 canal between the dorsal one and the lateral line pro- 

 per, but nearer the former; and forwards, from the 

 convex side of the l)ow, run the ordinary canal from 

 the mastoid region, continued on the side of the fore- 

 head to the nasal region, and also another, smaller 

 canal in the supraoccipital region as far as tlie inter- 

 orbital space, where it meets the corresponding canal 

 of the opposite side and united with this is continued 

 along the middle of the forehead as far as the anterior 

 orbital margin. In Caranx trachurus all these divisions 

 of the system of the lateral line have transverse bi'an- 

 ches at right angles to them, ^vhich in their turn send 



" Spot. Atl., 1. c, p. 53G, on Tracliurus Ciiiieri. 



'' This iiHMiibraiie, it is well known, docs not contain fat, bnt is ii liyalin(! (gelatinous) connective tissue (''^Gallei'tgewebe", Leydiq) tlie 

 presence of which rounil Ihe ninciferous canals of tishcs has already been remarked by Leydig (Lelirbucli der Hislolof/ie, p. 24). 



