KIKTKEN-Sl'INEl) STICKI.KHACK. 



fi89 



Icii^U'tli i)t' the stidiit i-i exMctly ot|iial to tlic distimcc 

 lii'twecn the liiiiil margin of tlie eye and that of 

 tlic ojiLTcuhiiii. This elongation of the snout is, Imw- 

 ever, a eiuiraeter of growth, foi- in fr\- "_M mm. long 

 the length of tiie snout is aliout tiu % of the [jost- 

 orbitnl length of tiie head, in young specimens between 

 50 and 7.') mm. long about ilO % thereof. The elonga- 

 tion is jirodueed, as we ha\e mentioned abo\c, by the 

 growtii in a forward dii'cetion of the ethmoidal region 

 and the palatine parts as well as of tlie preoperculum 

 and interopereulum. At the same time the quadrate 

 bone with the articular knob tVir the lower jaw moves 

 forward, and the eleft of the mouth, which up to the 

 present has been i-omi)arati\<'h' larger and almost hori- 

 zontal, becomes relatively smaller and rather more 

 ascending. \\ ith this elongation is also connected the 

 relative diminution of the eyes; in a specimen 21 

 mm. long their longitudinal diameter is equal to 

 tlie length of the snout, in specimens 25 mm. long 

 about ^ ,, in specimens 50 mm. long about ' ,, and in 

 •A female 172 mm. long only slightly more than '3 

 of the same length. 



The head is quadrangular, tapering in a forward 

 dii-ection, \vith per]3endicular sides and only slightly 

 convex occiput. The snout is depressed and blunt, 

 with the upper profile slightly concave. The eyes are 

 round, and their superior margin lies on a level with 

 the flat or somewhat hollow forehead, or rises a very 

 little above the latter, the breadth of which, at the 

 anterior margin of the eyes, is equal to their diameter. 

 The small, round nostrils, only one on each side, lie 

 half-way along the snout. The edges of the mouth are 

 furnished \\ith fleshv lips, lobate on the sides of the 

 upper jaw; the lower jaw projects beyond the upper, 

 which nun, however, be protruded bv means of the 

 long nasal processes of the intermaxillary bones. The 

 length of the lower jaw is al)ont '/j that of the snout. 

 When the moutii is closed, the small maxillaries, the 

 length of which is about ',2 that of the intermaxillaries, 

 drop under the projecting preorbital bones. The jaw- 

 teeth are of equal size, chisel-shaped, and most of them 

 notched at the margin; they are set in front Iti several 

 (3 or 4) fairly regular rows, behind in a single row. 

 The pharyngeal teeth are pointed, and above they form 

 on each side an almond-shaped card, obliquely divided 

 into an anterior, smaller patch and a po.sterior, larger 

 one. The gill-rakers are setiform, 10 or 11 in number 

 on the first branchial arch. The jjseudobranchia^ lie 



Scandinov'um Fishes. 



high, on each side within the articulation of the liyo- 

 maiidii)ular bone; each of them is nuule up of five, 

 digitiform lanielhe. set in a transverse row. Tiie ])ala- 

 tine fold of the iip|)er jaw is fairh' large, the corres- 

 ponding dermal fold in the lower jaw less developed. 

 The external bones of the head ai'e gi'anulated and 

 striated. The o|(erculuni is triangular, witli the hind 

 inferioi' side somewhat cimincx, the upper sidi' smue- 

 what concave. Ihe suboperculum lias a short, anterior 

 brancii in a vertical direction and a longer, posterior 

 one, broader below, tapei'ing behind, and curvtid like 

 a sai)re: the hitter forms the whole opercular mai'gin 

 along the lo\\(n' |)osterior side of the true ojierculum. 

 The preoperculum forms a right angle, with the an- 

 terior, horizontal arm, which is coasted by the subjacent 

 interoj^erculum, considerabl)- elongated, as we have 

 mentioned abo\e. The two posterior suborbital bones 

 are attached to the u]>iier (inner) margin of this arm, 

 the posterior firmly, the anterioi- very loosely, thus 

 forming a cuirass for the cheeks, but only under the 

 eyes. The hind part of the cheek (lietween the eye 

 and the vertical arm of the preoiierculum) and the space 

 between the long preorbital (first suborbital) bone and 

 the anterior part of the horizontal arm of the preoper- 

 culum (a strip along the side of the snout, behind the 

 corner of the mouth) are covered by the glossy skin 

 alone. The gill-openings extend above the operculum 

 for a distance measuring about ^3 of its length. Under- 

 neath the branchiostegal membranes are imited into a 

 broad, free fold, the hind margin of which coincides 

 with the anterior end of the interclavicles. 



The form of the trunk is determined principally 

 by the granulated plates that follow the dorsal margin, 

 the lateral line, and the ventral margins. The dorsal 

 margin is occupied bv the plates that have been deve- 

 loped in the skin on the tops of the interspinal bones. 

 Nearest to the occiput there lie two flat plates, one 

 behind the other, followed h\ a row of concave plates, 

 generalh' 15 in numlier, each of which is furnished 

 with a free spinous i-ay with a small, triangular mem- 

 brane behind it. Next follow seven plates, which 

 support the true, soft-rayed dorsal fin. On the dorsal 

 margin of the (ail this row is continued by fastigiated 

 and carinated plates, growing more and more flattened, 

 and finally smoothed out and indistinct. The ventral 

 edges are formed in the fore])art of the bodj- by the 

 interclavicles, which are coinjiaratively small in this 

 species, and which bv their arcuate union in front 



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