384 
SCANDINAVIAN FISHES. 
depth of the body, which occurs at its middle (exclud- 
ing the caudal fin), being about 2 / 5 of the total length 
to the end of the caudal fin a . The greatest thickness 
of the body always lies behind the head (in the ab- 
dominal region or the anterior part of the tail), and 
is more than V 3 °f the length of the head 7 '. 
The head is small, its length being always some- 
what less than that of the caudal fin, and varying in 
full-grown specimens between 1 5 % (according to Gott- 
sche 14%) and 167 2 % of the total length of the body, 
or between 18 and 20% of the length to the base of 
the caudal tin. The mouth is small, the gape being 
scarcely curved at all; and the jaws are of equal pro- 
jection and furnished with round, thick lips. The length 
of the lower jaw varies between 4 and 5 % of the length 
of the body or about 40 and 53 % of the least depth 
of the tail. The jaw-teeth are even, broad, and close- 
set in a single row; they are present in both jaws, but 
oftenest, in the upper jaw at least, only on the blind 
side. The eye side of the jaws is toothless or some- 
times furnished with 1 — 3 teeth. Sometimes one or 
two of the front teeth are longer than the rest. The 
upper pharyngeal teeth are comparatively few, 3 or 4 
on each of the three upper pharyngeals on each side, 
and are imbedded in a thick, loose skin on the roof 
of the pharynx. In shape they are flat, curved, trian- 
gular, and sharply pointed, like miniature Squaloid teeth. 
On the lower pharyngeals they are more scattered and 
narrower, more dagger-like c . The gill-rakers are middle- 
sized, setiform, and fairly close-set: we have found their 
number on the first branchial arch to be 22. The gill- 
openings are uncommonly small, partly because they 
do not extend higher than the top of the base of the 
pectoral fins — the entire upper margin of the opereula 
is united In 7 the skin to the body — partly because the 
branchiostegal membranes are in great part coalescent 
inferiorly, forming a fold upwards and inwards that 
fits into the bend of the urohyoid bone, above the point 
of the lower extremity of the clavicular bones. To this 
folding of the branchiostegal membranes is due the 
peculiarity that the last three of the seven branchio- 
stegal rays lie close together under the margin of the 
gill-opening; and as the first branchiostegal ray is small 
and almost invisible, the casual observer finds only three 
branchiostegal rays on each side. On the eye side of 
the body the margin of the gill-cover has a somewhat 
thick, orange rim, and a, similar rim appears on the 
clavicular bone (behind the margin of the gill-opening), 
in front of the base of the pectoral fin. The eyes are 
set on the right side, are large and very prominent, 
and lie so close together that they are separated only 
by a sharp osseous ridge. The longitudinal diameter of 
the upper orbit is fully half the length of the cranium 
from the head of the vomer to the large occipital fora- 
men; but the eyes themselves are so covered with der- 
mal folds that the visible part of the eye is compara- 
tively small. During the growth of the fish from 20 
to 30 cm. the length of the visible part of the upper 
eye diminishes, according to Kroyer’s measurements, 
from 28 V 2 to 1 9 1 / 2 % of the length of the head or, ac- 
cording to our measurements, from 2 6 1 / 2 to 2 1 V 3 % 
thereof. The lower eye, which is somewhat smaller 
than the upper, lies only a little further forward. The 
nostrils resemble those of the preceding species. They 
lie fairly near each other, on the eye side nearly in a 
line with the corner of the mouth and almost between 
the eyes. The nostrils of the blind side lie almost 
exactly at the dorsal edge of the snout, in front and 
to the right of the beginning of the dorsal fin, nearly 
in a line with the anterior margin of the upper eye. 
The scales cover both sides of the body, the head 
(excepting the eye side of the snout), the rays of the 
vertical fins, the outer side of the base of the pectoral 
fins and of half the ventral fins, and sometimes a part 
of the inner side of the last pair of fins as well. They 
are thin, smooth at the margin, oval, and (on the body) 
imbricated. On the head they are nearly round, smaller 
than on the body, and not imbricated. The lateral line 
is straight, with a slight, but distinct, arched curve above 
the pectoral fins. This arch seems generally to be higher 
on the blind side than on the eye side, but its height 
and shape are subject to individual variations. 
The dorsal fin begins somewhat behind the anterior 
margin of the upper eye, but distinctly on the blind 
a In this respect this species is more variable than the preceding one. According to our measurements of 6 specimens between 15 
and 31 cm. long, from Bohusliin and Norway, the greatest depth of the body varies between 35 and 38% of the length to the end of the 
caudal fin, or 42 1 /, and 46 % of the length to the base of the caudal fin, the proportions being highest in the largest specimens. According 
to Gottsche the former proportion varies between 36'/ 2 and 45%, and according to Kroyer between 32 and 40%. 
b According to our measurements the greatest thickness of the body varies between 34 and 40 % of the length of the head, accord- 
ing to Kroyer’s measurements between 40 and 43 % thereof. 
c Kkoyer has found them to be set in two rows. In our specimens they are set in a single row. 
