274 



SCANDINAVIAN FISHES. 



]>uint, strongly depressed and tliin, resembling a lal)ial 

 fold which covers the upper jaw, and underneath which 

 the latter niaA- be drawn in. The margin of the upper 

 jaw, wliich ])rojects bevond the lower, is formed by the 

 fairly firmly united and somewhat arcuate intermaxillary 

 l)ones, which form a kind of beak. These bones are 

 furnished with long nasal jn'ocesses, which slide along 

 the facial bones, and contribute to tlie marked pro- 

 trusion of the upper jaw, when the mouth is opened. 

 The latter then accjuires a tubular appearance, and is 

 turned olili(|uelv downwards, as we hnA'e endeavoured 

 to show in the outline drawing in Plate XIV. The 

 maxillar} bones are verj* small, situated behind the 

 intermaxillaries and hidden by the labiate skin of the 

 snout, their lower end being visible only when the 

 mouth is opened and protruded. Both jaws are fur- 

 nished with fairly Heshy lips and very small, cardiform 

 teeth. There ai'e no teeth on the palate or on the 

 tongue, which is small, cartilaginous and rounded to a 

 point, with a. small, soft rim round the free tip. A 

 small, transverse, membranous fold appears on the pa- 

 late, but there is no corresponding fold below it. The 

 eyes are set high and close to each other, l)ut are turned 

 in a lateral direction, the eyeballs, which project above 

 the level of the forehead, being superiorly depressed. 

 Tiie pupil is kidne}'-shaped, there being a lol)ate process 

 in the u[)per margin of the iris. The nostrils are veiy 

 small and are set quite close to the eyes; the anterior 

 opening is somewhat tubular, the posterior almost in- 

 visible. At the lower corner of the |)re(jperculum ^ve 

 find a projecting hand-shaped process, which is gener- 

 ally furnished at the end with .3 pointed, subulate spines, 

 directed upwards and backwards, and interiorly with a 

 si>ine pointing forward, whicii lies, however, along the 

 base of the process, hidden by the skin, and is there- 

 fore easily overlooked. The fish is not unskilled in the 

 use of these weapons. When an attempt is made to lift 

 it, it expands the gill-covers, like the Bullheads, the 

 spinous processes being thus erected. The operculum 

 is small and very thin, with soft, cartilaginous margin. 

 The gill-openings are small round holes on each side 

 of the occiput, with a thin, loose membrane at the 

 margin, which closes them like a. valve. The remainder 

 of the opercular margin is unite<l to the body by the 

 skin. Tile branchiostegal mcnd)rane is furnished with 

 6 rays, all tine and soft, with hairlike tips, the u]iper- 

 raost three being especially long and bent round the 



" Somelimes only 7. 



opercvdar margin. The branchial cavity is narrow, ^vith 

 small gills and narrow openings between the arches; 

 the anterior margins of the latter are furnished ^vith 

 two rows of small, verrucose, osseous protuberances (gill- 

 rakers). The upper pharyngeals are loosely united into 

 tM-o i-ounded almond-shaped plates, entirely rough with 

 fine, cardiform teeth. The lower pharyngeals are (jf the 

 ordinary oblong shape, and are armed in the same way. 



The skin of the body is throughout thin and smooth, 

 without any trace of scales, and covered with an abun- 

 dant mucous secretion. At several spots it is so loosely 

 attached to the body that it may be raised into folds. 

 The lateral line is scarcely visible, but runs in the form 

 of a, somewhat raised seam along the middle of the 

 sides, its course being fairly straight, though somewhat 

 winding. It advances out to tlie hind margin of the 

 caudal tin, lying between the third and fourth rays 

 thereof. Straight across the occiput there runs a con- 

 necting-duct between the two lateral lines. On the 

 hind part of the body, from the middle of the second 

 dorsal fin, we generally find ti'ansverse branches of the 

 lateral line, alternately in an upwai'd and a downward 

 direction, one I'unning straight up, and the next, which 

 is shorter, obliquely doAvnwards. One or two such 

 branches rise from the latei'al line on each side, meet- 

 ing at the dorsal edge, just in front of the caudal hn, 

 and thus forming connecting ducts. The vent is situ- 

 ated in front of the middle of the body, almost verti- 

 cally below the second ray of the second dorsal tin. 



Two dorsal tins rise from the depression which runs 

 along the dorsal edge. The anterior is triangular, and 

 begins above the upper angle of the base of the pec- 

 toral tin, at a distance from the middle of the point of 

 the intermaxillary bones, when drawn back, which mea- 

 sures from 2.5 to 28 % of the length of the body. It 

 contains only four, simple, soft-tipped rays, which are 

 followed l)y the fin-membrane out to the very tip. The 

 first ray is the longest, the others gradually diminish- 

 ing in length. The second dorsal tin, which begins near 

 the end of the first, generally contains eight" simple 

 rays, all of which are articulated, and at the end one 

 ray branched down to the base, and with the branches 

 also divided at the tip. The length of its base de- 

 creases with age from about 26 to 23 % of the length 

 of the body. The anal hn is of the same shape and 

 structure as the second dorsal, but begins a. little farther 

 back than the latter, the distance between it and the 



