GREAT FORKED BEARD. 
541 
the least depth of the body (tail) varies between 37s » 
(in youth) and 4 % (in old specimens) of the length 
of the body or between 27 and 34 % of the length 
of the lower jaw. 
In full-grown specimens the head partakes of the 
general compression of the body. Above it is flat or 
slightly convex, and its flat sides, the cheeks, are al- 
most parallel to each other. The length of the head 
varies with age" between about 22 and 23 % of that 
of the body. The eyes are rather oblong and fairly 
large, the longitudinal diameter of the orbits varying 
with age between about 6 7 2 and 5 % of the length of 
the body or 30 and 22 % of that of the head. They 
are set in the second third of the head, though the 
length of the snout varies between about 28 and 33 % 
of that of the head, and the postorbital length of the 
head between about 42 and 50 % of the total length 
thereof. The nostrils are set in the last third of the 
snout, on about a level with the centre of the eye, the 
distance between them being about the same as that 
between the posterior one and the margin of the orbit. 
The anterior nostril, which is a small, round opening, 
is marked by a lobate elevation of the hind superior 
part of the margin; the posterior is twice as large and 
oblong, without any elevation of the margin. The tip 
of the snout projects beyond the margin of the upper 
jaw, and the latter in its turn beyond the tip of the 
lower jaw. The whole snout is soft and of a loose 
structure, this being due to the extensive development 
within it of the muciferous ducts of the system of the 
lateral line. The opercular apparatus is most like that 
of the Hake, with triangular, almost forked operculum. 
The suboperculum is thin but broad, and pointed at 
the top (behind); it lies under and tills the deep inci- 
sion in the hind posterior margin of the operculum, 
while the inner part of its truncate, anterior (lower) end 
touches the interoperculum, which is thicker but nar- 
rower. Thus the margin of the entire opercular appa- 
ratus is somewhat incised at this point. The preoper- 
culum, with its broad margin (to receive the muciferous 
duct) is rectangular but rounded at the angle. The 
branchiostegal membranes are united into a collar under- 
neath, but this collar terminates posteriorly almost ver- 
tically below the centre of the eye. The jaws resemble 
those of the Cod. The maxillary bones extend back 
to the perpendicular from the hind margin of the pupil, 
the intermaxillaries being a little shorter and reaching 
only to the perpendicular from the anterior margin of 
the pupil. The distance between the tip of the snout 
and the hind extremity of the maxillary bones is greater 
than the postorbital length of the head and more than 
half the total length of the head, but less than the 
length of the lower jaw, which varies between GO and 
53V 2 % of the length of the head or between 33 and 
28 % of that of the base of the anal fin. The post- 
orbital length of the head is thus always less than the 
length of the lower jaw, but increases with age even 
in this relation, from about 70 to 90 or 91 %. The 
length of the barbel under the chin is somewhat less 
than that of the eye. The teeth are most like those 
of the Burbot, being small and of uniform size, but 
set in a dense card in the lower jaw and on the inter- 
maxillary bones and in a curve, somewhat pointed in 
front, on the head of the vomer. The palatal folds 
behind the jaw-bones are narrow but distinct, at least 
in the lower jaw. The tongue is flat and broad, with 
a narrow, free tip and margin. The gill-rakers, 14 or 
15 in number on the first branchial arch, are well- 
developed, but not of any great length. The phar- 
yngeal teeth resemble the jaw-teeth. 
The first dorsal tin begins at a distance from the 
tip of the snout that varies with age between about 
25 and about 29 % of the length of the body, and it 
terminates close to, but quite distinct from the begin- 
ning of the second dorsal tin. When erected it has the 
form of an almost right-angled triangle with the right 
angle at the hind corner and with the shortest side 
(the base) measuring about 6 or 7 % of the length of 
the body. As a rule the first three rays are simple, 
and the third ray is elongated into a filament about 
twice as long as the fourth ray, which, like the others, 
is branched. The first ray is about half as long as the 
second, which is somewhat shorter than the fourth. 
The variations in this respect are, however, considerable, 
and the elongated ray sometimes projects only slightly 
above the others, its length varying, even in adult spe- 
cimens, between about 10 and 17 % of that of the body. 
The second dorsal fin begins at a distance from the tip 
of the snout of 32 — 36 % of the length of the body, 
and its base, taking into account the individual varia- 
tions, measures between 51 and 53 % of this length. 
Its height is fairly uniform, but greatest (9 or 10 % 
Here and in the following relations the changes of growth are given as we have found them in specimens between 18 and 57 cm. long. 
