564 



SCANDINAVIAN FISHES. 



usual, behind (outwards). The gill-rakers are short and 

 scattered — about 13 in number on the first branchial 

 arch, l)ut the foremost (lowest) and uppermost ones 

 liardly distinguishable — tubercular and spiny. The 

 branchial arches ai-e complete, but the fourth (hindmost) 

 is united throughout the greater part of its length to 

 the hind wall of the branchial cavity, the last gill-slit 

 thus being rather small. The mouth is without trans- 

 verse folds (vela). The barbel under tlie chin is equal 

 in length to tlie longitudinal diameter of the eye or 

 even longer". The Ijranchiostegal membranes are united 

 lielow for a great part of their Ijreadth. Tlieir hind 

 margin forms a fairly regular curve, ^vithout distinct 

 opercular flap. The whole gill-cover is imbedded in 

 the skin; and the gill-opening does not extend to its 

 superior margin, the upper corner of the gill-opening 

 Iving on about a level with the middle of the eye. 



The dorsal tin begins at a distance from the tip 

 of the snout equal to about 27 '/^ — '2b'% % of the length 

 of tlie liody, and thus moves forward with age, while 

 the length of its base sho>vs even relative increase from 

 al)out 61 '4 % to rather more than 65 % of the length 

 of the body. The number of the rays seems also to 

 increase at the same time, from about 90 to 105, which 

 latter number we have found in a fish 64 cm. long. 

 The fin rises in a very elongated arch, its greatest 

 height (where the length of the rays is about 9^/2 — 8 

 % of that of the body) lying about Vs of the ■way along 

 the tin; Imt the last rays sharply diminish in length, 

 and the Hn ends in a bluntly pointed lobe, with half 

 its hind margin coalescent with the upper margin of 

 tlie caudal fin. The division lietween these two fins 

 may, however, l)e traced internally as well, for the last 

 ray in the dorsal fin is nmltifid, the uppermost raj' in j 

 the caudal fin simple, as Avell as the first two or three 

 rays of tlie dorsal hn. The anal fin is of the same 

 structure and form as tiie dorsal, but not ([uite "/g 

 {()1 — 64'/2 %) as long. It is also lower, and its union 

 to the caudal hn shorter. It Ijegins at a distance from 

 ilie tip of the snout tliat measures between 52 or 53 

 and 51 % of the length of the bod}', and the length of 

 its base seems to vary individually between 37 Vg ;ind 

 41' '2 % of the same length. At the ends of the dorsal 

 and anal fins the tail tapers to a point from above and 

 below, thus forming a triangular base for the caudal 

 hn. This fin is broadly rounded, almost as in the 



Burbot, and its length at the middle is in young spe- 

 cimens more, in old less, than the depth of the tail at 

 the beginning of the fin. In our largest specimen, 

 which is 64 cm. long, the caudal fin contains 46 rays, 

 the uppermost two and the lowest two simple. 



The pectoral fins are rounded and of average size 

 or smaller, their length varj'ing in different individuals 

 between 12 and 10 % (sometimes 9V2 %) of that of the 

 liody. In tlie specimen just mentioned they are made 

 up of 24 rays, only the uppermost ray being simple. 



The ventral hns are of a more characteristic form. 

 They are rather long, sometimes (in young specimens) 

 longer than the pectoral fins, Init narrow and of uni- 

 form breadth, this being due to the fact that the last 

 (hindmost) ray is only slightly shorter than the first, 

 which in its turn is a little shorter than the three 

 middle rays, and like them projects a little way beyond 

 the common membrane. All the rays are simple and 

 ^vith extremely numerous articulations, but may be 

 easily divided in two halves throughout their length 

 from the very base. The fins are set in about a line 

 with the upper corners of the gill-openings, but move 

 forward, as usual, with age, the distance between them 

 and the beginning of the anal fin rising in adult spe- 

 cimens from about 28 to 31 % of the lenijth of the 

 body. The distance between the anterior ends of their 

 insertions is half the length of the lower jaw. 



All the hns are covered with skin, thick at the 

 base, but growing thinner towards the margin, which 

 renders the counting of the rays without dissection 

 difficult and uncertain. 



The scales extend over the whole body and head, 

 except the very tip of the snout and the lips, out over 

 all the fins, right to the thin margins, which are naked. 

 They are linguiform, thin, and small — extremely small 

 on the head and fins — largest, as usual, on the caudal 

 part of the body, and everywhere densely imbricated. 

 The largest scales in a specimen 64 cm. in length are 

 about 5 mm. long and 2 mm. broad at their broadest 

 point, which lies where they project from their follicles 

 in the skin, in which they are imbedded for the greater 

 part (about ''/j) of their length. Their structure is 

 essentially the same as that of the scales in the genus 

 Molua, and they are furnished Avith a moniliform mark- 

 ing produced in the same way (see above, p. 521 and 

 note h), but still more closely resemble the scales of 



" In our ytiungesl siieciiiK-n inncli slidrtoi-. 



