226 
SCANDINAVIAN FISHES. 
the length, and in specimens about 270 mm. long 
about 5'6 %. From the occiput to the vent the body, 
which is almost terete, is of uniform depth as well; 
but behind this point it becomes more and more com- 
pressed, even knife-shaped, and also gradually dimi- 
nishes in depth to the base of the caudal fin, where 
the depth of the body is about 2 % of the length. 
The head is fairly short in proportion to the length 
of the body; but its relative length varies considerably 
according to age: in specimens 50 mm. long, according 
to Collett, the length of the head is about 18 % of 
that of the body; in specimens 154 mm. long it has 
proved to be 13*6 %\ in specimens 271 mm. long 11 '2 
%j\ and in specimens 320 mm. in length, according to 
Collett, 9'7 %. The occiput is convex, the forehead 
somewhat compressed, and the superior profile of the 
head slightly curved, with the snout sloping more 
steeply. The gape is only slightly turned upwards, 
almost horizontal, and the snout projects slightly beyond 
the under-jaw. The eyes are fairly large, the longi- 
tudinal diameter being 24 or 23 % of the length of 
the head. There seem to be three pairs of nostrils, 
two of which, however, are very small, simple openings, 
most resembling the pores of the lateral line, the an- 
terior pair being situated just behind the articulation 
knobs of the maxillary bones, and the posterior in front 
of the anterior upper corner of the eye on each side. 
Between these two openings on each side we find a 
fairly large, tubular papilla, which should probably be 
regarded as the true nostril 0 . The maxillary bones 
are rather short, and somewhat wider posteriorly than 
in front. Their length is from 22 to 28 % of that of 
the head. The intermaxillary bones, on the other hand, 
are narrow, but with fairly large nasal processes. The 
upper jaw, however, admits of scarcely any protrusion. 
The intermaxillary teeth are small and cardiform, but 
in the outer row there are several teeth of larger size 
than the others. The lower jaw-teeth are set in one 
row, or anteriorly in two. The palatine bones and 
vomer, as well as the tongue, which is rounded, are 
without teeth. Beneath the point of the chin a knob, 
which increases in size with age. The operculum and 
suboperculum, together with the posterior dermal flap, 
form a triangle, the base of which is about half the 
distance from the point of the flap, which fits into the 
upper corner of the axil, to the hind margin of the 
eye. The branchiostegal membranes are entirely free 
from each other, and are not united to the isthmus 
until they reach its front part. There are six, aeinaci- 
form branchiostegal rays, the first of which is extra- 
ordinarily small. 
The scales are small, and at the middle of the 
body, on the upper half of the sides, above the lateral 
line, 18 scales may be counted in a transverse row. 
The scales which cover the tumid (muscular) cheeks, 
are still smaller. The system of the lateral line is 
most highly developed on the head, but even there the 
pores are generally distinct only in the row which runs 
along the hind margin of the preoperculum, and from 
this point downwards on the lower side of the branches 
of the under-jaw * * 6 . The pores of the lateral line of the 
body are scarcely distinguishable, but the line runs in 
a groove straight along the middle of the sides. 
The vent lies a little behind the end of the first 
third of the body. In accordance with the changes of 
growth mentioned above it is relatively situated farther 
forward in old specimens than in young. In a speci- 
men 154 mm. long the distance from the vent to the 
tip of the snout is 37*7 % of the length of the body, 
in another, 230 mm. in length, 35'7 %. 
The pectoral fins seem pointed, when folded; 
but, when expanded, they prove oval, with evenly 
rounded margin. Their relative length diminishes with 
age: while the length of the body increases from 150 
to 270 mm., the length of these fins decreases from 10 
to 7 1 / 2 % of that length; but while the length of the 
body increases from 150 to 230 mm., the length of 
these fins relatively to the length of the belly between 
the insertion of the ventral fins and the beginning of 
the anal fin, suffers but very little change, measuring 
about 40 % thereof. All the rays are articulated, and 
all, except the first- (uppermost) may be branched; 
sometimes, however, the last (lowest) ray is also simple. 
The ventral fins are pointed, and, in young specimens 
a Of. Stuwitz, Kroyer and Lilljeborg. The tubular structure of this papilla is generally more easily distinguished in Lumpenus 
Fabricii. In the Sharp-tailed Lumpenus it is, in most cases, difficult to find any opening at the top of the papilla. 
6 The system of the lateral line on the head is most distinct in young specimens, especially in Lumpenus Fabricii , where a row of 
pores lies in a furrow on each side of the temporal region, from the articulation of the preoperculum to the eye. The preopercular row of 
pores runs from the end of this furrow, in a downward direction, and, from its beginning, the row belonging to the suborbital ring, is con- 
tinued forward on the snout, along the lower margin of the preorbital bone. In this species, the lateral line of the body, anteriorly at least, 
is furnished with distinct pores. 
