SMELT. 
871 
Its length, which shows with fair uniformity even re- 
lative increase with age, varies between 12 1 / 2 and 1 (5 1 / 2 
% of that of the body, between about 60 and 76 % of 
that of the head, or between about 86 and 98 % of 
that of the head reduced. The mouth and pharynx 
with their dentition have already been described. The 
gill-rakers are set in one row of 34 — 37 on the first 
branchial arch, and are setiform, tine, dense, and long. 
The pseudobranchhe compose a narrow, longitudinal 
band on each side, made up of about 10 short, trans- 
versely set threads, just behind the boundary between 
the palatine arch and the branchial cavity, and running 
straight back from the upper insertion of the first 
branchial arch. The operculum is quadrilateral, trape- 
zoidal, with the upper margin shortest, the posterior 
slightly concave at the top, and the inferior straight. 
The length of the last-mentioned margin, which is di- 
rected obliquely backwards and upwards as in the Sal- 
mons, varies in different individuals between about 32 
and 24 % of that of the head. The suboperculum also 
resembles that of the Salmons, being rather narrow but 
of uniform breadth, and rounded at the lower posterior 
corner. The interoperculum is triangular, most pointed 
in front. The preoperculum is rounded at an obtuse 
angle. The gill-openings are large, extending up above 
the middle of the superior opercular margin and down 
to a level with the centre of the eyes. The branchio- 
stegal membranes are broad and thick, free both from 
each other and the isthmus; but at the extreme front 
they cross, the left overlapping the right. The first- 
two (three) branch! os tegal rays are slender, setiform; ' 
the other five sabre-shaped, gradually increasing in 
breadth backwards (upwards). 
The dorsal tin begins at a distance from the arti- 
cular knob of the maxillaries that increases with age 
from about 46 to 50 % of the length of the body. Its 
base varies between about 7 1 / 2 and 8V2 %■> and its 
greatest height (the length of the 3rd or 4th ray) be- 
tween about 14 and 15 %, of the length of the body. 
Above it is obliquely truncate, with the upper posterior 
margin straight or somewhat convex. The adipose fin 
is of the same shape as in the Salmons, but of a di- 
stinctly fibrous texture. It is situated above the poste- 
rior part of the anal fin, at a distance from the caudal 
fin measuring about Vio — Vs (9 Vs — 12 Vs 0/0 ) °f the 
length of the body. The anal fin begins at a distance 
from the articular knob of the maxillaries equal to about 
70 % (69 1 /, — 72 Vs %) of the length of the body, the 
percentage being generally greatest in the females. The 
length of its base varies between 14 and 11 %, and its 
greatest height (the length of the 3rd — 5th ray) between 
10 and 8 1 /s %, of the length of' the body. Its inferior 
margin is somewhat concave. The caudal fin is deeply 
forked, the length of the middle rays being only slightly 
greater than (sometimes equal to) the least depth of the 
tail, or about 2 / 5 (varying between 35 and 43 %) of 
the length of the longest caudal rays, which varies be- 
tween about 17 and 15 % of that of the body. 
The pectoral fins are set as in the Salmons, rather 
low. When folded, they are of an obliquely pointed 
shape; when expanded, oval. Their length varies be- 
tween 16 and 14 % of that of the body. The third 
(second branched) ray is commonly the longest. The 
ventral fins are of a broader shape, and are always 
shorter. Their length varies during growth between 
147 2 and 12 % of that of the body. Their distance 
from the tip of the snout (i. e. from the articular knobs 
of the maxillaries) is generally the same as that of the 
dorsal fin. The preabdominal length is as a rule more, 
the postabdominal length less, than 1 / i of the length of 
the body, the former varying between about 29 and 
26 % , the latter between about 22 and 23 % thereof. 
The structure of the scales we have already de- 
scribed. Below Ave shall see hoAV the scales of the lateral 
line indicate the origin of those of Argentina and Sco- 
pelus, as a transition stage in this respect between the 
said genera and the Capelin. During the spawning- 
season both the males and females are covered with a 
granulate dermal eruption, Avhich varies, hoivever, con- 
siderably both in prominence and extent. 
The internal organs and the most important pecu- 
liarities of the skeleton have also been described in 
the preceding pages. 
The coloration is principally characterized, here as 
in the following genus, by the thinness and transpa- 
rency of the scales; and this transparency is commu- 
nicated in some degree both to the dorsal musculature 
and the head, the vertebrae as Avell as the cerebral 
parts being visible in the living fish. The back and 
the upper portion of the head are pale green or some- 
times dashed with bluish gray, and doAvn the sides, 
especially in the breeding males, this colour passes into 
a lustrous violet. Along the middle of the sides runs 
a silvery band, and this silvery lustre extends to the 
shoulder-girdle, the opcrcula, and the cheeks. Under 
the scales the skin is strewn on the upper parts of the 
Scandinavian Fishes. 
110 
