843 



is always convex, never tttit as in tlie llucli. Its length, 

 whicii is generally greater in the males tliaii in the 

 females, varies in the Northern Charr between about 



20 and 22 % of that of the body, in the Siclbling 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 

 fairlv low, near the maxillary bones. They are nearly 

 round, the longitudinal diameter being only slightly 

 greater than tlie vertical, and varying between about 



21 and 12 % (exceptionally 8^/4 *) of the length of 

 the head; hut 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 '/g (30 — 35 %") 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 fuiniel; 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, o\ving 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 ihe hyoid bone are indeed ir- 

 regular in occurrence, but rarely wanting. The niaxil- 

 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. Tlie lower jaw, which in most old 

 specimens ]jrojects a little beyond tlie tij) of tiie u]jper 

 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 iiead. The preoperculum is crescent- 

 shaped. Tiie 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 Huch 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 \vhich spines at least rudiments are pre- 

 sent in the Salmons, is entirely wanting in the Scan- 

 dinavian Charrs. The pseud obranchia; 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, Ijut sometimes (in a form \vhich has 

 been named alijies'') as much as %, 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 



" In the Charr reared at the hatchery of Ostaiibiick this percentage was lower, sinking oven to 27. In .\rctic Cliarr (var. stagnalu) 

 it may rise even to 39. 



' Salmo alipes, Richardson, Fn. Bor. Amer., pt. Ill, p. 169, tab. 81 et 86 fig. 1. Cf. Smitt. Hiksin. Sabnonid., lab. III. fig. 50, 

 a similar form, a male with strongly developed fins, taken in Torne& Trsesk. 



