488 



SCANDINAVIAN FISHES. 



SO high that the line fi'om t!ie tip of tlip gill-cover to 

 ihe mai-gin of the ujiper j;iw touelies the lower edge 

 of the pupil. Tlie least hreadth of the interorbital space 

 alters with iiidix idiial variations between about 25" and 

 and 27 % of the length of the head. The nostrils lie 

 somewliat nearer to the e}-e than to tlie snout, just 

 below the outer margin of the forehead. The anterior 

 opening on each side is small and round, witli the upper 

 ])Osterior part of the mai-gin raised into a canaliculate 

 flap which rises backwards. The posterior opening is 

 larger, oval, and open, witliout any elevation of the 

 margin. The mouth is set almost horizontallv, with 

 the upper jaw longer tlr.m the lower. The gape is 

 large, and admits of consideral)le expansion, partly by 

 means of the tensile ligaments that unite the apparatus 

 of the jaws to the corners of the mouth, and partly by 

 means of the movable gill-co^■ers and the free branchio- 

 stegal membrane. The margin of the upper jaw is 

 i'ormed, as in most of the Physoclysts, l)y the inter- 

 maxillarv bones alone, which are shorter than the maxil- 

 lary bones behind them. The hind extremity of the 

 latter bones is truncate, with a Ijreadth aliout equal 

 to V(; of ^he lengtli of the lower jaw or, in adult spe- 

 cimens, somewhat less than half the longitudinal dia- 

 meter of the eye. ^^'hen the mouth is closed, the en- 

 tire upper jaw falls into a deep fold formed by a straight, 

 labiate flap which extends on both sides from the snout 

 to a point vertically below the front corner of the eye, 

 to a distance from tlic ti]) of the snout only slightlj- 

 less than the postorl)ital length of the liead or some- 

 times equal to it. The up]3er jaw itself surrounds the 

 lower. When the moutli is oj^en, the upi)er jaw pro- 

 jects a little beyond the tip of the snout. The lower 

 jaw, the length of which is about 12 V, or 13 % of the 

 length of the bod}- or half' that of tlie head, is gener- 

 ally Avithout an)- distinct liarbel; but under the chin 

 we tind a small pointed protuberance or a rudiment 

 thereof, and in a fe-\\- young specimens a very small 

 and short barbel, Avhich generall)- escapes observation. 

 Pointed, subulate teeth are pi-esent in both jaws 

 and on the head of the vomer; but l)oth the tongue 

 and the ])alatine bones are smooth. Tlie teetli are set 

 in each jaw in only one regular row, but in the front 

 part of tlie month, in the upper jaw within this i-ow, 

 in the lower jaw outside it, we find numerous smaller 

 and finer teeth in irregular rows. The teeth are some- 



what larger in the lower jaw than in the upper, and 

 in the foi-mer they are larger at the sides than in front. 

 The tongue is fairly long, cartilaginous, and thick, with 

 narrow, triangular tij). 



The hindmost of the four branchial arches is united 

 throughout its whole length to the pectoral wall, the 

 last branchial slit being thus closed on each side. Each 

 arch is furnished in front with two rows of bouA- tu- 

 bercles, covered by the mucous membrane, but tlie 

 outer ro\v on the tirst arch is made uji of true gill- 

 rakers, like narrow lamelhe, which are three times as 

 narrow and long as the other tubercles. The branchio- 

 stegal membrane, with its seven rays, is tirndv iniited 

 underneath to tlie membrane of the other side, but 

 deeplj' incised; and the margin itself is not united to 

 the isthmus. The gill-cover ends in a point, but this 

 is hidden by the broad flap (a continuation of the 

 liranchiostegal membrane) which, as Ave have mentioned 

 above, forms a margin round the whole of the gill- 

 cover. 



The body is covered with small, thin, imbricate 

 scales, set in ratlier irregular roAvs. These scales are 

 scarcely visible in living specimens, especially while tlie 

 surface of the body is moist and covered Avith mucus; 

 but they grow fairly distinct in large specimens and Avhen 

 the skin has had some time to dry. They also cover 

 the Avhole head, Avith the exception of the upper jaAv 

 and the extreme upper margin of the lower jaAv. (^)n 

 close examinati(jn Ave find that they advance a good 

 Avay over the caudal fin and impei'ce[)tiljly disappear 

 toAvards its end, and also clotlie the l)ase of the first 

 anal fin and the branchiostegal membrane, extending a 

 little Avay along the rays of the latter. Distinct traces 

 of scales may also be found at the front jjart of the 

 base and the anterior margin of all the other fins. 



The course of the lateral line is S-shaped, as in 

 most of the Codfishes, being curved lieloAV the second 

 dorsal fin. It forms a continuous, narrow groove, wliich 

 has, as it Avere, an articulated appearance, partly on 

 account of the small, short, lateral grooves that jut 

 out at fixed intervals, and partly on account of its 

 being filled u]) here and there on the tail, and thus to 

 a certain extent effaced. 



The vent lies at the end of the first third of the 

 length of tlie liodv and a little in front of the |)er- 

 pendicular from the middle of the first dorsal fin. 



" Occasionally 24Vo %. 



'' Sonietiiiies only 48 %. 



