374 SCANDINAVIAN FISHES 



The l)raiirli of the blind side is oidy slightly 



toothless 



changed in the articular (posterior) part, but the an- 

 terior oi- dental |iart is much shortened, deeper than 

 long, of an irregular quadrilateral shape, toothless in 

 front, and heliind, in the toothed part, curved out- 

 wards — somewhat as in Mufjil — and still farther l^ack 

 raised into a process which meets, and is united by 

 strong ligaments to, the hind part of the intermaxillary 

 bone. The brancii of the lower jaw on tlie Itlind side 

 is thus much deeper, but shorter than that on the eye 

 side, its depth being about ^/j the least depth of the 

 tail or t^vice the longitudinal diameter of the eye. There 

 are on each side three round, upper pharyngeals — the 

 middle one being considerably larger than the other 

 two — and one oblong, lower pharyngeal. All of them 

 are set with mova])le, cardiform teeth, like the jaw- 

 teeth. The gill-o|)enings are small; the opening on the 

 blind side extends up to the top of the insertion of 

 the pectoral fin, liut on the eye side only to the lower 

 end of this insertion. The opercula have rounded, smooth 

 margins and are entirely covered ^vith a thick, scaly 

 skin, Ijut under tlieir rims protrudes the margin of the 

 smooth, scaleless bi'aiichiostegal membrane. The two 

 branchiostegal membranes are united underneath, and 

 surround the anterior lower point of the clavicular bones, 

 at the point where the latter are united to each other 

 and to the lower posterior prong of the urohyoid (basi- 

 branchiostegal) bone. The latter bone is shaped, as in 

 most of the Flatfishes, like a joiners square, the end 

 of tlie anterior (longer) prong being attached to the 

 under surface of the hyoid bone, and tlie posterior prong 

 pointing in a downward direction and united by a liga- 

 ment to the to]) of the lower junction of the clavicular 

 bones. Thus, the two clavicular bones a.nd the uro- 

 hyoid bone are united in front into a point, which is 

 generally covered underneath bv the coalescent branchio- 

 stegal membranes, 'iliere are usually 6 or 7" branchio- 

 stegal rays on each side, sharply bent, and covered 

 bv the opercula. The outer (distal) part of the first 

 branchiostegal I'ay on one side is coalescent with the 

 corresponding ))art ol the same ray on the other side. 

 The eyes are oblong, and less prominent tlian in the 

 rest of the Scandinavian Flatfishes. The upper eye lies 

 half its own length in frtnit of the lower, \vhich is 

 situated above and close to the corner of the mouth. 

 The distance between the eyes is about equal to the 

 longitudinal diameter of the iris. The pupil is round, 



" GoTTSCHE has soinc'times found 8 branchiostegal rays. 



without an-^- intruding excrescence from the iris. The 

 skin of the l)o(l\- may be drawn over the eye in the 

 form of an eyelid. The nostrils are more or less per- 

 fectly tubular. The nostrils of the eye side are set 

 close to eacii otiier and near the anterior margin of the 

 lower eye, close to the mouth, the anterior being per- 

 fectly tubular, the posterior larger, with the tube slit 

 behind. The nostrils of the blind side, on the other liand, 

 are far apart, the posterior being situated fairly high 

 above the corner of the mouth and the anterior about 

 half-way between the posterior and the tip of the snout. 



The surface of the body is even, and covered on 

 both sides with imln-icate, oblong scales, rounded at the 

 corners and distinctly ciliated behind. The scales cover 

 the surface of the eye side of the head entirely, but 

 only two-thirds of the surface of the blind side, the 

 anterior third of this side of the head (the mouth and 

 snout), as well as a part of the base of the dorsal fin and 

 the margins of the operculum of this side, being thickly 

 strewn with soft tubercles or warts, with a crest of short, 

 haii'like cirri at the tip. The fin-rays are also covered 

 with scales, at least for some distance from the base. 

 The ravs of the vertical fins are each fni-nished -witli 

 several rows of more or less pointed scales, and on the 

 eye side this covering extends almost out to the ti[)s 

 of the rays. The paired fins are covered with scales 

 only on the outer surface of the rays and for about 

 half their length. On the blind side too, the covering 

 of scales does not extend so far out on all the fins, 

 and the ventral fin of this side (sometimes the pectoi'al 

 as well) is generally scaleless. Behind the head the 

 lateral line is distinct and perfectly straight, or slightly 

 curved in the abdominal region, where it also lies nearer 

 the dorsal than the ventral margin. But the cephalic 

 system of the lateral line is indistinct, with the ex- 

 ception of the dorsal l)ranch, which curves upwards and 

 forwards in an arch on the occiput. The vent lies very 

 far forward, between the ventral fins and just in I'ront 

 of the beginning of the anal fin, entirely on the blind 

 side, but close to tiie ventral margin. Just behind the 

 vent lies the genital opening, and between them we find 

 a dermal flap, which is sometimes erected in the sliape 

 of an acute-angled triangle. 



The dorsal fin is fairly low, somewhat higher in 

 the males than in tlie females, its longest rays measur- 

 ing about 20 — 23 % of the greatest de]:)th of the body, 

 91—92 % of the least depth of the body or 40-45 % 



