488 
SCANDINAVIAN FISHES. 
so high that the line from the tip of the gill-cover to 
the margin of the upper jaw touches the lower edge 
of the pupil. The least breadth of the interorbital space 
alters with individual variations between about 2 5“ and 
and 27 % of the length of the head. The nostrils lie 
somewhat nearer to the eye than to the snout, just 
below the outer margin of the forehead. The anterior 
opening on each side is small and round, with the upper 
posterior part of the margin raised into a canaliculate 
flap which rises backwards. The posterior opening is 
larger, oval, and open, 'without any elevation of the 
margin. The mouth is set almost horizontally, with 
the upper jaw longer than the lower. The gape is 
large, and admits of considerable 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-covers and the free branchio- 
stegal membrane. The margin of the upper jaw is 
formed, as in most of the Physoclysts, by the inter- 
maxillary bones alone, which are shorter than the maxil- 
lary bones behind them. The hind extremity of the 
latter bones is truncate, with a breadth about equal 
to 7 g °f the length of the lower jaw or, in adult spe- 
cimens, somewhat less than half the longitudinal dia- 
meter of the eye. When 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 the tip of the snout only slightly 
less than the postorbital length of the head or some- 
times equal to it. The upper jaw itself surrounds the 
lower. When the mouth is open, the upper jaw pro- 
jects a little beyond the tip of the snout. The lower 
jaw, the length of which is about 12 1 / 2 or 13 % of the 
length of the body or half* that of the head, is gener- 
ally without any distinct barbel; but under the chin 
we find a small pointed protuberance or a rudiment 
thereof, and in a few young specimens a very small 
and short barbel, 'which generally escapes observation. 
Pointed, subulate teeth are present in both jaws 
and on the head of the vomer; but both the tongue 
and the palatine bones are smooth. The teeth are set 
in each jaw in only one regular row, but in the front 
part of the mouth, in the upper jaw within this row, 
in the lower jaw outside it, we find numerous smaller 
and finer feeth in irregular rows. The teeth are some- 
" Occasionally 24 If, %. 
b Sometimes only 48 %. 
what larger in the lower jaw than in the upper, and 
in the former they are larger at the sides than in front. 
The tongue is fairly long, cartilaginous, and thick, with 
narrow, triangular tip. 
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 bony tu- 
bercles, covered by the mucous membrane, but the 
outer row on the first arch is made up of true gill- 
rakers, like narrow lamella?, which are three times as 
narrow and long as the other tubercles. The branchio- 
stegal membrane, with its seven rays, is firmly united 
underneath to the membrane of the other side, but 
deeply 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 
branchiostegal membrane) which, as we have mentioned 
above, forms a margin round the whole of the gill- 
cover. 
The body is covered with small, thin, imbricate 
scales, set in rather irregular rows. These scales are 
scarcely visible in living specimens, especially while the 
surface of the body is moist and covered with mucus; 
but they grow fairly distinct in large specimens and when 
the skin has had some time to dry. They also cover 
the whole head, 'with the exception of the upper jaw 
and the extreme upper margin of the lower jaw. On 
close examination we find that they advance a good 
way over the caudal fin and imperceptibly disappear 
towards its end, and also clothe the base of the first 
anal fin and the branchiostegal membrane, extending a 
little way along the rays of the latter. Distinct traces 
of scales may also lie found at the front part 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 below the second 
dorsal fin. It forms a continuous, narrow groove, which 
has, as it were, 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 up 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 the body and a little in front of the per- 
pendicular from the middle of the first dorsal fin. 
