956 



SCANDINAVIAN FISHES. 



tlie luaxillaries we liave to distiuguisli, ;is among' the 

 Vaiidaces, between the more terete, introrse, artieular 

 shaft, which supports the intermaxilhiries on its up- 

 turned, grooved, and proximally broader, front surfsiee, 

 and tlie lateral jjai't, set almost at right angles to the 

 former, luid indeed terete in front, but soon expanding 

 into the Hat, sabre-shaped disk that forms the extcr- ! 

 ually visible maxil]ar\'. This pai't is obtusely rounded 

 Ixdiind and toothed with spines at the thin lower uiar- 

 gin, and bv the additi(.)ii of the supi)lementary bone is I 

 retifleied fnrly uniform in breadth throughout the 

 greater part of its length. The po-sterior supplementary 

 (jugal) bone is elliptical, and in front pointed, the an- 

 terior narrower and of uniform breadth. The length 

 of the lateral maxillary disk, measured from the arti- 

 cular knob, varies on an average between 10 and 8^/3 % 

 of that of the body or between 47 and 44'/2 "i of that 

 of the head, and the lione extends back to a line with 

 the anterior margin of the jnipil or even -with its centre, 

 though ahvays so that the length of the cheek (between 

 the maxillary and the vertical anterior margin of the 

 preoperculum) is greater than its height exactly beloAV^ 

 the eve. The cheek is covei-ed by the large, third 

 suborbital bone, which also forms the greater jmrt of 

 the posterior limit of the orbit, the fourth (hindmost) 

 suborbital bone being comparatively short. The lower 

 jaw is characterized bv the rather great heiglit of the 

 dental part — about twice the breadth of the maxillaries 

 or "'5 of the length of the lower jaw — and by the ter- 

 ete ridges on the outside <if this part, which diverge 

 Ijackwards from each side of the chin, one of them run- 

 ning along the u]>per margin, tlie other jjarallcl to thi^ 

 lower margin. The s^'inplivsis is also fairlv higii, and 

 is furnished below with a small, jjrominent chin-protu- 

 berance, but channelled underneath at its angle. Only 

 at tlie extreme front of the upper margin do \ve tind 

 an arcuate row of small teeth ((> on each side of the 

 S3'mphysis), in well-marked, but closely approximated 

 sockets. The length of the lower jaw varies between 13 

 and 12 ?^ (in the oldest specimens 11 ??/) of that of the 

 body, or 60 and 57 % (exceptionalh' 61 % or, in the 

 oldest specimens 55 ^) of that of the head, and it is 

 greater, as a rule, than the length of the base of the 

 anal tin, though in exceptional cases this relation too 

 is reversed. ( )n the symphysis and the sides of the 

 lower jaw hangs a fairly In'oad labial fold. Internally 

 the mouth is furnished with the ordinarj' transverse 

 folds (vela), the- lower being the more developed. The 



\()mer has in front a longitudinal, lanceolMte elevation, 

 bearing a double rnw of small, pointed teeth, somewhat 

 larger, however, than the jaw-teeth; and a shorter row 

 of smaller teeth usuallv occuyjies the extreme front of 

 each palatine. Tiie tongue is Iree and fleshv, but tliin- 

 margined. <h\ tlie glosso-lnoid bone is an almond- 

 shaped card of small ti'eth. The gill-rakers are set in 

 a single row on most of the branchial arches, long and 

 setiforin, \vitli numerous small spines on their sides. 

 (_)n the first branchial arcli there are aljout 70, as a 

 rule 45 — 47 (exceptionally 44 oi- 50) on the lower part 

 thereof, and the longest (at tlie middle of the arch) are 

 about (Hjual in length t(j the subojierculum at its suture 

 with the operculum. ( >nlv on the upper ])art of the 

 third arch and on the fourth arch as far as it forms 

 the anterior margin of the short, hindmost gill-slit, do 

 we find an inner (posterior) row of .short, lamellate 

 rakers. About 20 s])ines, similar in form to the latter, 

 occu]:)V the outside of the lower phar\'iigeals, whiidi re- 

 semble branchial arches, and are furnished with only 

 one row of small teeth, whei'eas the upper pharyngeals 

 bear a triangular card of similar teeth. The outer gill- 

 openings ai'e lai'ge, extending above the u))per margin 

 of the operculum, from a level with the superior mar- 

 gin of the eye, down to a line with the anterior margin 

 of the latter. The operculum is obliquely quadrilateral, 

 with the iq)per posterior corner rounded and the lower 

 anterior corner pi'olongated to an acute angle, so that 

 the faint S-shape of the subopercular suture is directed 

 obliquelv backwards and upwards. The length of this 

 suture varies liet'ween 23 (exceptionally 21' .,) and 26 

 (exceptionally 27) "o of that of the head. On the sur- 

 face of tile operculum we can distinguish three slightly 

 convex patches, sejjarated bj' two shallow grooves, one 

 running obliquely backwards and upwards, the other 

 oblicjuely backwards and downwards, from the articular 

 head of the ojierculum. But these j)atches are smooth 

 or marked only with faint concentric stria', and the an- 

 terior lower patch in jjarticular is destitute of radiating 

 grooves or ridges. The suboperculum resembles a nar- 

 row, eccentric sector of a circle, varying in breadth; 

 sometimes its margin' shows an irregular, shallow in- 

 dentation. The preoperculum is obtuse at the inner 

 angle, but the lower posterior corner forms a n)unded 

 right angle, lis posterior disk is so broad that its length 

 (the lower arm together with the disk) is about equal 

 to its height (the vertical arm together with the disk). 

 The interoperculum is triangular and equal in length 



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