928 
SCANDINAVIAN FISHES. 
brane by which they are connected. The adipose tin 
behind the dorsal tin is long and low. 
The anal tin, which begins just behind the vent, 
is longer but lower than the dorsal fin proper, and the 
hind part of its margin is deeply concave. The distance 
between it and the tip of the snout is about 61 — 63 % 
of the length of the body, and its base measures about 
17 — 18 % of the same. In the distribution of the rays 
we observe that the first seven and the last four are 
set more or less close together at the base, but that 
the eighth ray is more widely separated both from 
the seventh and the ninth, and points straight down- 
wards, its direction thus converging with that of the 
seventh ray. 
The caudal fin is deeply forked. The length of 
the middle rays is 8 % of that of the body, and ap- 
pears to be perceptibly less than half (at most about 
46 %) of that of the longest rays. At the upper mar- 
gin of the fin lie 9, at the lower 6, short but com- 
paratively thick and hard supporting rays, the anterior 
directed outwards (respectively upwards or downwards). 
In the suspensory apparatus of the pectoral fins, the 
uppermost bone, probably answering to the supra-cla- 
vicular bone — in which case the posttemporal bone is 
wanting — is bent at a right angle. Its upper, shorter, 
horizontal arm is straight and of uniform breadth, 
attached to the median line of the occiput — not at 
the side, where the posttemporal bone is attached in 
other fishes — and its lower, vertical arm, which is 
somewhat broader and forms a thin expansion in front, 
rests upon the upper part of the clavicle. The angle 
between the arms forms a short spine, directed back- 
wards, and both arms are coursed on the outside by 
a longitudinal groove, bounded by ridges and hollowed 
into grooves similar to those in the upper part of the 
temporal region (see above). The ridges and grooves 
are continued on the outside of the vertical part of the 
clavicle in front of the pectoral fins, and below the 
latter the clavicle sends out, in the skin, a backward 
process, flat and of uniform breadth, but curved up- 
wards like a sabre, and with similar grooves on the 
outer surface. The inferior part of the clavicle ex- 
pands forwards and inwards to a thin, vertical blade, 
projecting straight downwards in a pointed spine, which 
marks the limit between the sloping isthmian region 
and the horizontal ventral margin. The pectoral fins 
are obliquely set; when at rest, they point upwards 
and backwards. They are rather long, but narrow and 
obliquely pointed. The third or the fourth ray is the 
longest, but only slightly longer than the second. The 
first ray, which is the only simple one, is a little 
shorter than the second; the last (10th) occupies about 
2 / lt of the length of the fin, which measures somewhat 
more than 1 / 4 (26 — 27 %) of that of the body. 
The ventral fins are set undermost on the ascend- 
ing break in the ventral margin, with their insertions 
close together and vertically situated, the first ray, 
which is simple but, like the others, compressed, being 
thus the lowest, and the under side of these fins in 
other fishes being here turned inwards". In shape the 
ventral fins are oval, and their length is about equal 
to the height of the anal fin, 8 1 / 2 — 9V 2 % of the length 
of the body. The lowest point in their insertions 
lies at a distance from the tip of the snout measuring 
nearly 2 / 3 (62 1 / 2 — 65 %) of the length of the body, 
and the distance between this point and the foremost 
point in the insertions of the pectoral fins (the pre- 
abdominal length) is about 29 — 30 % of the same 
length. The postabdominal length, which ascends but 
breaks off at an angle, measures in a straight line 
about 14V 2 — 15 % of the length of the body. The 
thin pelvic bones, which are vertically set, share in 
the structure of the septum between the luminous spots 
of the preabdominal margin. But at the lower poste- 
rior corner each of the pelvic bones projects in a spine, 
and sends out above this spine an ascending process* 
which joins the lower part of the hindmost preabdo- 
minal rib, while the lower tips of the preceding ribs 
touch the squamous growths that enter into the struc- 
ture of the sharp ventral margin and bear its lumi- 
nous spots. 
The greater part of the body — except the black 
or grayish brown back — is covered with a thin, sil- 
very skin; but according to v. Duben and Koren 
scales are also present, though these are thin and deci- 
duous. “These scales are rather large (about 2 x / 2 mm. 
long in a specimen 65 mm. in length), smooth with 
entire margin, and of a bright silvery lustre like their 
underlayer. Under the microscope they gleam with all 
the colours of the rainbow, but not even then does 
a This is also the case, as we have seen above (p. 426), in Botkina, but is there due to an entirely different structural peculiarity. 
b Cf. the analogous structure in the Sticklebacks, see above, p. 635, fig. 157, A, vs. 
