CAPELIN. 
877 
towards the ventral margin, which is narrower, but 
terete. The ventral profile in front runs almost pa- 
rallel to the dorsal, beginning to rise towards the pe- 
duncle of the tail at the origin of the anal fin, in the 
females uniformly, but in the males with a break 
caused by the arcuate expansion of the base of the 
said fin. 
The shape of the head reminds us most of a three- 
sided pyramid, two sides of the pyramid being formed 
by the cheeks, which approach each other below, and 
the third by the flat forehead and occiput. Its length, 
which is greatest in the females and the young, varies 
between 23 and 19 % of that of the body, and the 
length of the head reduced, from the articular knobs 
of the maxillaries to the hind margin of the preoper- 
culum, similarly between 15'/ 2 and 13 % of the length 
of the body. The horizontal profile of the tip of the 
snout is broadly rounded, but its breadth at the arti- 
culation of the maxillaries is considerably less than in 
the Smelt, measuring only 1 fi — 20 % (in exceptional 
cases 21 %) of the length of the head. The length of 
the snout, on the other hand, is greater than in the 
Smelt, being about 33 — 30 % of that of the head. The 
eyes are also comparatively larger than in the Smelt: 
in adult Capelins their longitudinal diameter, which is 
somewhat greater than the vertical, is about 24 — 23 % 
of the length of the head. The postorbital length of 
the head is consequently always less in the Capelin 
(about 44 — 48 %) than half the length of the head, 
while in the Smelt it is more than half of the same. 
The forehead is flatter, but its breadth, like that of 
the snout, is on an average less than in the Smelt, 
being only about 24 — 22 % of the length of the head, 
and in exception to the general rule in the family, it 
is the males that here represent the earlier stages of 
development. In the opercular apparatus the operculum 
itself is of the same shape as that of the Smelt, but 
the sinus at the hind margin is indistinct or wanting. 
The suboperculum is somewhat larger than in the Smelt, 
and more nearly resembles the quadrant of an ellipse. 
The lower posterior angle of the preoperculum is al- 
most a right angle. That portion of the margin of the 
upper jaw which is formed by the intermaxillaries 
measures only about % — 5 / 7 (63 — 74 %) of the longi- 
tudinal diameter of the eyes; but the length of the 
maxillaries is about the same as in the Smelt, on an 
average about 41 %, varying between 38 and 44 %, of 
that of the head. The length of the lower jaw, on an 
average less than in the Smelt, is about 57 %, varying 
between 55 (exceptionally 53) and 60 (exceptionally 
62) %, of that of the head; but the more essential 
difference in the shape of the lower jaw between these 
two genera is due partly to the downward convergency 
of the sides of the head in the Capelin, the halves of 
the lower jaw being thus brought nearer to each other, 
partly to the less marked curvature in an upward di- 
rection of the point of the lower jaw, which, however, 
projects, even in the Capelin, beyond the tip of the snout. 
As regards the distribution of the teeth in the mouth, 
palate, and pharyiix the Capelin in all essential respects 
resembles the Smelt; but all the teeth of the Capelin 
are of uniform size and small, about equal in size to 
the maxillary teeth of the Smelt. On the true hyoid 
bone (os linguale or glossohyale ) lies an elliptical row 
of teeth within the fleshy margins of the tongue, with 
one or two teeth set inside the ellipse, and on each 
mesopterygoid bone the row of teeth is not situated, 
as in the Smelt, .at the very inner margin, the bone 
having grown further inwards to form a more com- 
plete bottom for the orbit. The gill-rakers resemble 
those of the Smelt, but are as a rule somewhat more 
numerous, 35 — 39 on the front of the first branchial 
arch, and 25 — 30 of these on the lower part of the 
same. The pseudobranchise lie just behind the orbits 
and above the dermal fold that bounds the palate be- 
hind. They consist of 15 or 16 short lamellse, set in 
an oblique transverse row. The gill-openings are large, 
extending from about half the upper edge of the oper- 
culum to a line with the anterior margin of the eyes, 
and the two branchiostegal membranes are entirely free 
from each other, crossing only to an extremely small 
extent in front, where the left membrane overlaps the 
right, but Avhere each is covered by an outer fold of 
the skin, the right fold lying outside the left. The first 
(lower) four branchiostegal rays are slender and subu- 
late, the last (upper) 4 — 6 gradually become flatter 
and broader (sword-shaped) behind (upwards). 
The dorsal fin begins at a distance from the arti- 
cular knobs of the maxillaries that measures about 50 
— 55 % of the length of the body, farthest back as a 
rule in the females. Its base measures about 1 / 10 (9 
— 12 %) of the length of the body, and is generally 
somewhat less (but sometimes, especially in the males, 
somewhat greater) than its height as expressed by the 
length of the longest (3rd and 4th, i. e. first branch- 
ed) rays. When erected, the fin is of an obliquely 
