HERRING. 
957 
to the preoperculum. Its externally visible part (below 
the preoperculum) is, however, sword-shaped and of 
uniform breadth. The hind margins of the preoperculum 
and interoperculum together form a slightly curved line, 
continued below the latter in a contour forming an 
obtuse angle with the inferior margin of the suboper- 
culum. In the Herring, as in the other Clupeoids, 
we find a bone that seems at first sight to be a lower 
suboperculum, forming an angular break at the lower 
posterior angle of the opercular apparatus. In order 
that the apparatus may be more firmly closed at this 
angle, the anterior margin of the shoulder-girdle rises 
at this point in the form of an elongated, sharp-edged 
knob, the substratum of which consists of an upright 
process {dp, fig. 238, p. 950) from the upper margin 
of the horizontal arm of the clavicle. On closer exa- 
mination, however, it soon appears that the apparent 
lower suboperculum is really tire hindmost of the three 
broad branchiostegal rays set on the epihyoid bone. 
The first five rays, which are situated on the cerato- 
hyoid bone, are subulate and more curved. The branchio- 
stegal membranes are free both from each other and the 
isthmus, and overlap each other only to a very small 
extent in the extreme front, the left membrane lying 
outside the right. 
The dorsal fin, which is trapezoidal in shape, begins 
at a distance from the tip of the snout (the articular 
heads of the maxillaries) measuring 47 — 51 % of the 
length of the body. The length of its base is 13 — 10 %, 
and its greatest height (the length of the first or second 
branched ray) 12 — 10 % (less frequently 9 %), of the 
length of the body. The anal fin is of a similar shape 
as the dorsal but much lower. The distance between 
its beginning and the tip of the snout is 71 — 75 %, the 
length of its base 11 — 10 % (exceptionally 12 or 9 %), 
and its greatest height 5V 2 — 4V 2 % (exceptionally 6 or 
4 %), of the length of the body. The caudal fin is 
deeply forked, the lower lobe being somewhat longer 
and more pointed than the upper. Its middle rays 
occupy about 5 — 4 % of the length of the body, and 
measure only V 3 — 1 / i of the length of the longest rays 
in the fin. 
The pectoral fins are set low, as in the Salmons, 
and of an oval, obliquely pointed shape, the second 
branched (third) ray being usually the longest. Their 
length varies between 16“ and 13 % of that of the body, 
and during youth is generally somewhat more, in old 
specimens perceptibly less, than half the preabdominal 
length, which increases even relatively with age, from 
30 to 35 or nearly 36 % of the length of the body. 
The ventral fins are broader and shorter, but triangular. 
Their length varies between 10 and 8 % of that of the 
body. Their insertion always lies some distance, though 
in young specimens this is sometimes very small, behind 
the perpendicular from the beginning of the dorsal fin, 
and at a distance from the tip of the mouth measuring 
51 b — 55 % of the length of the body. The postabdo- 
minal length is about 2 /s of the preabdominal, and 
varies between about 20 and 23 % (exceptionally 24 %) 
of the length of the body. 
The thin and deciduous scales (fig. 239) are round 
or quadrilateral with rounded angles. The hind (free) 
part is indented at the margin with small, rounded 
sinuses, and shows only faint traces of radiating grooves. 
The anterior part (covered and about twice as large) is 
Fig. 239. Scale from the left side of a Clupea liarengus 
3 dm. long. X 3. 
smooth-margined and marked with extremely fine and 
numerous, irregularly undulating and confluent, trans- 
verse striae, without radiating grooves or with only ru- 
diments thereof, in the form of a few streaks (5 — 7 
upwards and downwards) obliquely crossing the others. 
In this striature the growth-rings of the scale also 
appear as concentric lines. The lateral line does not 
pierce any scales — only in exceptional instances are 
there a few perforated scales in front — but under the 
scales it runs straight from the upper clavicle to the 
middle of the base of the caudal fin. The singular 
marginal scales of the belly (fig. 240) are of an oblique 
diamond-shape, with a strengthening ridge in the me- 
dian line of the belly, ending in the backward spine, 
and another on each side, continued by the upward 
process. They are remarkable in the Herring for their 
number, which is greater than in the following species, 
being as a rule, according to Heincke, 27 — 30 (excep- 
a In young Herrings sometimes 17. 
b In the fry sometimes 5 0 1 / 2 . 
