184 



SCANDINAVIAN FISHES. 



membrane, wliich is suj)j)oi'tecl by six rays, is united 

 under the middle of the throat (the isthmus) to the 

 corresponding membrane on the other side by a con- 

 tinuation of its skin, which is here of almost the same 

 breadth as itself, and has an even, transverse margin, 

 ]K)steriorly free. When both the branchiostegal mem- 

 I)ranes are expanded, thei-e thus appears a large arcu- 

 ate collar round tlie head. The nostrils are small, 

 forming on each side two funnel-shaped, dermal ducts, 

 which are separated by tlic nasal Ixme, the one open- 

 insf Ivinc on the side of and close to the anterior mar- 

 ein of the eve, the other in front of the latter and 

 somewiiat nearer it than the tip of the snout. The 

 eyes (cf. the above table) are fairl)' large — their longi- 

 tudinal diameter varies between ^ ,, (iu young speci- 



mens) 



anc 



1/ 



(in old) of the length of the head — 



and so close together tliat the space between them, 

 which is concave, is narrower than their diameter. The 

 pupil is I'ound; in some specimens oval, with the more 

 ])ointed end directed forwards. The head is armed with 

 several spinous processes — first -with two, pointed, 

 conical spines in front of the eyes and between the 

 nostrils, projecting from the sides of the nasal bone 

 and movable; and secondly with four fixed spines on 

 its top, which point in a backward direction, one at 

 the superior margin of each eye and one on each side, 

 at the end of the occiput. Between the latter runs a 

 bar on each side of the top of the head, that on one 

 side being nearly |)arallel to that on the otlier. The 

 four last spines, which look like small horns, have given 

 rise to the name of Hornskalle (Hornhead). Sometimes 

 they are wanting, and in their stead we find more or 

 less sharp tubercles. The fishermen hence believe that 

 tliese horns are shed or knocked off in some way du- 

 ring the spawning-season. On the margin of the pre- 

 operculum we generally tind tln-ee (sometimes four) 

 strong spines. The uppermost is the largest and jjoints 

 in a backward direction; it never extends so far back, 

 however, as the o])ercular spine, wliich points in the 

 same direction as it. The second is next to it in size 

 and also directed backwards: sometimes the tips of both 

 ])roject above the thick skin which covers them. The 

 other two are short and flat: the fourth points down- 

 \vards and the third is often wanting, or present on 

 one side of the body and wanting on the other. The 

 operculum ends iu a long, ])i'o)ecting spine (the oper- 

 cular spine) and a still longer, thin, dermal margin. 

 The suboporculuHi has two spines in its lower margin; 



the one points doAvnward and is the longer, the other 

 is turned inwards in a forward direction and is hidden 

 by the preopei'culum. The interoperculum, as usual, 

 has its upper posterior corner prolonged into a spine, 

 which is directed backwards, but is scarcely visible, as 

 it lies under the point of the do\vnward s])ine of the 

 suboperculum. There is also a long spine, Avhich lies 

 under the skin and is directed backwards, on the tiaie 

 clavicular bone, and a similar one on the upper cla- 

 vicular I)one. The lateral line is raised, but totally 

 luiarnied. It lies near the back, and follows the dorsal 

 curve to the end of the second dorsal tin, at about the 

 30th pore iu the line counted from the beginning, 

 where it curves slightly downwards and then termin- 

 ates at the middle of the base of the caudal tin. On 

 each side of the line are scattered irregularly strewn, 

 stiff scutes, of a singular nature, generally differing in 

 the different sexes. In the male they are large, flat, 

 rounder, depressed at the centre and cup-shaped, with 

 from 3 to 5 or more stiff' points, turned outwards in a 

 backward direction or set in the margin of the Avhole 

 scute; in the female they are smaller and narrower, 

 nearly oblong. \\\{\\ oidv 1 or 2 spines. In the latter 

 sex, too, they are not ahvays present, for one may tind 

 specimens entirely without them, others with extremely 

 few, and so forth. The body tapers coiiicallv towards 

 the tail and is rounded, ^\•\\\\ the caudal part laterally 

 compressed to some extent. The back, which rises 

 somewhat to the 3rd tin-rav and then slopes evenly 

 towards the tail, has its two tins quite distinct, but often 

 set very close together. The iirst dorsal tin is more 

 convex, shorter and lower than the second; its two first 

 ra5^s are usuallv close together at the base. In Scandi- 

 navian specimens the number of rays varies bet^veen 

 8 and 10, all simple, pungent and curved slightly back- 

 wards; in Arctic specimens it is most often 11. The 

 posterior dorsal tin is larger, with rounded margin, and 

 in Scandinavian specimens contains from 14 to 16, in 

 Arctic often 17 and sometimes even 19, simple, articul- 

 ated and weak rays. The ])ectoral tins are large, as is 

 the rule in the genus, oblong and rounded, Avith from 

 15 to 17 simple, articulated, round and thick rays. The 

 7th and 8th ra}S are the longest, and the fin then 

 sharply diminishes in length to the last ray, the length 

 of which is only ' ^ or ' ., of that of the first (upper- 

 most) ray. As is generalh- the case in the genus, the 

 tips of tlie lowest rays extend someAvhat ])eyond the 

 fin-membrane. The ventral fins are long (cf. the aljove 



