CIIAKR. 
843 
is always convex, never flat as in the Huch. Its length, 
which is generally greater in the males than in the 
females, varies in the Northern Charr between about 
20 and 22 % of that of the body, in the Sadbling be- 
tween about 23 and 24 % of the same. The eyes are 
middle-sized or rather, in old specimens, small; they 
are always set in the anterior half of the head and 
fairly low, near the maxillary bones. They are nearly 
round, the longitudinal diameter being only slightly 
greater than the vertical, and varying between about 
21 and 12 % (exceptionally 8 3 / 4 %) of the length of 
the head; but the outer orbital margin is prolongated 
in front to a point, and the anterior canthus formed 
in this manner is filled by an adipose membrane. The 
breadth of the convex forehead above the centre of the 
eyes is about i / 3 (30 — 35 % a ) of the length of the head. 
The nostrils of each side are set close to each other, on 
about a level with the upper orbital margin and half as 
far from the eyes as from the tip of the snout. The 
anterior nostril on each side is round, with the margin 
raised in a funnel; the posterior is obliquely placed and 
oblong. The length of the snout, which in young spe- 
cimens is shorter and blunter than in old, and in adult 
males longer and more pointed than in females of the 
same size, varies between 26 and 36 % of that of the 
head. The mouth is large, owing to the elongation of 
the snout even relatively larger in old specimens than 
in young. The cleft of the mouth ascends somewhat, 
though only a little. The teeth, the extent of which 
we have above considered, are rather small, but strong 
and pointed, with the tip recurved. The small teeth 
on the copular parts of the hyoid bone are indeed ir- 
regular in occurrence, but rarely wanting. The maxil- 
laries, which are generally straight, but in old males 
curved downwards behind, extend in the young hardly 
behind the perpendicular from the posterior orbital 
margin, but in old specimens some way beyond it. 
Their length is greatest in the males, and varies in 
Scandinavian Charr from about 35 to 46 % of that of 
the head; and their greatest breadth, which thus be- 
comes comparatively less as a rule in the males than 
in the females and in old specimens than in young, 
varies between about 25 and 18 % (exceptionally 15 %) 
of their length. The lower jaw, which in most old 
specimens projects a little beyond the tip of the upper 
jaw, and has a small protuberance at the end that fits 
into an indentation in the latter, measures in the males 
about 60 — 75 in the females about 57 — 65 %, of 
the length of the head. The preoperculum is crescent- 
shaped. The operculum and suboperculum together 
form a parallelogram, usually somewhat wider below, 
and with the lower posterior angle rounded. The suture 
between them, the length of which may serve as an 
expression for the breadth of the opercular apparatus, 
is comparatively shorter in old Charr than in young 
and also as a rule, in the males than in the females, 
its length varying between about 26 and 20 or even 
17 % of that of the head. The branchiostegal mem- 
branes coalesce with the isthmus in a line with the 
anterior part of the eyes, or even in front of the per- 
pendicular therefrom. The gill-rakers are fairly nu- 
merous in comparison with those of the Iluch and 
Salmon, numbering 23 (exceptionally 20) — 27 in the 
outer row on the front of the first branchial arch, about 
15 (13 — 16) of these being situated on the lower, pro- 
jecting part of the arch. The inner row of spines on 
this arch, of which spines at least rudiments are pre- 
sent in the Salmons, is entirely wanting in the Scan- 
dinavian Charrs. The pseud obranchise are distinct in 
young specimens, concealed in old. 
The true dorsal fin is obliquely quadrilateral (tra- 
pezoidal), the length of the last ray being as a rule 
less than half, but sometimes (in a form which has 
been named alipes b ) as much as 2 / 3 , of that of the first 
branched ray. The latter is as a rule the longest ray 
in the fin, but in young Charr is sometimes a little 
shorter than the second branched ray. The distance 
between the fin and the tip of the snout increases even 
relatively with age, this depending principally on the 
prolongation of the snout, and is as a rule greater in 
the males than in the females, varying between about 
42 and 46 % of the length of the body. Its base mea- 
sures about 10 — 11 %, and its height about 11 (ex- 
ceptionally 10) — 15 (exceptionally 17) %, of the length 
of the body. The adipose (second dorsal) fin, which 
lies above the posterior part of the anal, is rather small 
a In the Charr reared at the hatchery of Ostanback this percentage was lower, sinking even to 27. In Arctic Charr (var. stagnalis) 
it may rise even to 39. 
b Salmo alipes , Richardson, Fn. Bor. Amer., pt. Ill, p. 169, tab. 81 et 86 fig. 1. Cf. Smitt, Riksm. Salmonid ., tab. Ill, fig. 50, 
a similar form, a male with strongly developed fins, taken in Tornea Trsesk. 
