564 
SCANDINAVIAN FISHES. 
usual, behind (outwards). The gill-rakers are short and 
scattered — about 13 in number on the first branchial 
arch, but the foremost (lowest) and uppermost ones 
hardly distinguishable — tubercular and spiny. The 
branchial arches are complete, but the fourth (hindmost) 
is united throughout the greater part of its length to 
the hind wall of the branchial cavity, the last gill-slit 
thus being rather small. The mouth is without trans- 
verse folds (vela). The barbel under the chin is equal 
in length to the longitudinal diameter of the eye or 
even longer". The branchiostegal membranes are united 
below for a. great part of their breadth. Their hind 
margin forms a fairly regular curve, without distinct- 
opercular flap. The whole gill-cover is imbedded in 
the skin; and the gill-opening does not extend to its 
superior margin, the upper corner of the gill-opening 
lying on about a level with the middle of the eye. 
The dorsal fin begins at a distance from the tip 
of the snout equal to about 27 V 2 — 25 3 / 4 % of the length 
of the body, and thus moves forward with age, while 
the length of its base shows even relative increase from 
about 6IV3 % to rather more than 65 % of the length 
of the body. The number of the rays seems also to 
increase at the same time, from about 90 to 105, which 
latter number we have found in a- fish 64 cm. long. 
The fin rises in a very elongated arch, its greatest 
height (where the length of the rays is about 9 1 / 2 — 8 
% of that of the body) lying about V 8 of the way along 
the fin; but the last rays sharply diminish in length, 
and the fin ends in a bluntly pointed lobe, with half 
its hind margin coalescent with the upper margin of 
the caudal fin. The division between these two fins 
may, however, be traced internally as well, for the last 
ray in the dorsal fin is multifid, the uppermost ray in 
the caudal fin simple, as well as the first two or three 
rays of the dorsal fin. The anal fin is of the same 
structure arid form as the dorsal, but not quite 2 / 3 
(61 — 64 V 2 %) a s long. It is also lower, and its union 
to the caudal fin shorter. It beo-ins at a distance from 
o 
the tip of the snout that measures between 52 or 53 
and 51 % of the length of the body, and the length of 
its base seems to vary individually between 37 1 / 2 and 
4lV 2 0/0 of the same length. At the ends of the dorsal 
and anal fins the tail tapers to a point from above and 
below, thus forming a triangular base for the caudal 
fin. This fin is broadly rounded, almost as in the 
Burbot, and its length at the middle is in young spe- 
cimens more, in old less, than the depth of the tail at 
the beginning of the fin. In our largest specimen, 
which is 64 cm. long, the caudal fin contains 46 rays, 
the uppermost two and the lowest two simple. 
The pectoral fins are rounded and of average size 
or smaller, their length varying in different individuals 
between 12 and 10 % (sometimes 9 1 / a %) of that of the 
body. In the specimen just mentioned they are made 
up of 24 rays, only the uppermost ray being simple. 
The ventral fins are of a more characteristic form. 
They are rather long, sometimes (in young specimens) 
longer than the pectoral fins, but narrow and of uni- 
form breadth, this being due to the fact that the last 
(hindmost) ray is only slightly shorter than the first, 
which in its turn is a little shorter than the three 
middle rays, and like them projects a little way beyond 
the common membrane. All the rays are simple and 
with extremely numerous articulations, but may be 
easily divided in two halves throughout their length 
from the very base. The fins are set in about a line 
with the upper corners of the gill-openings, but move 
forward, as usual, with age, the distance between them 
and the beginning of the anal fin rising in adult spe- 
cimens from about 28 to 31 % of the length of the 
body. The distance between the anterior ends of their 
insertions is half the length of the lower jaw. 
All the fins are covered with skin, thick at the 
base, but growing thinner towards the margin, which 
renders the counting of the rays without dissection 
difficult and uncertain. 
The scales extend over the whole body and head, 
except the very tip of the snout and the lips, out over 
all the fins, right to the thin margins, which are naked. 
They are linguiform, thin, and small — extremely small 
on the head and fins — largest, as usual, on the caudal 
part of the body, and everywhere densely imbricated. 
The largest scales in a specimen 64 cm. in length are 
about 5 mm. long and 2 mm. broad at their broadest 
point, which lies where they project from their follicles 
in the skin, in which they are imbedded for the greater 
part (about 74) °f their length. Their structure is 
essentially the same as that of the scales in the genus 
Molua, and they are furnished with a moniliform mark- 
ing produced in the same way (see above, p. 521 and 
note b), but still more closely resemble the scales of 
In our youngest specimen much shorter. 
