830 
SCANDINAVIAN FISHES. 
Salmon ( Oncorh . tschawytscha ), has been introduced 
with success by piscicultural methods not only into the 
Eastern States of North America, but also into Australia 
and Europe, though not yet, to the best of our knowledge, 
into Scandinavia. The Scandinavian fauna has, how- 
ever, been enriched in very recent years, according to 
a newspaper paragraph at the beginning of 1892, by 
the introduction from Germany of a form planted in 
the latter country, the Californian Rainbow Salmon 
( Salmo irideus). The said form, together with a Charr 
form — or rather an intermediate form between the 
Salmon and Charr — has its original home west of the 
Rocky Mountains and in the Pacific Ocean, although 
they both belong to the course of development other- 
wise represented only to the east of this mountain 
range. A closer examination of these forms leads us, 
however, to the result" that in them we have a blending 
of characters most naturally to be explained, if not on 
the assumption of hybridism, as a reminiscence of the 
time when the Salmon and Charr, in their common de- 
velopment, were not fully differentiated from each other. 
Another American form, a Charr from the Eastern 
States (Salma fontinalis), has been cultivated with suc- 
cess in England, Wales, and Scotland. Salmo fontinalis 
is also an intermediate form between the Salmon and the 
Charr, the only character — though not of great vali- 
dity — in which it differs from the Greenland Charr, 
the absence of teeth on the basibranchial bones (hyoid 
teeth), being a character of the Salmon 6 . The Brook- 
Trout (S. fontinalis) has been crossed both here and 
in America with the Salmon as well as with European 
Charr; and these experiments have taught us, among 
other things, that the character which otherwise com- 
poses a constant distinction between Salmon and Charr, 
the feeble ossification and toothlessness of the vomer in 
the latter, loses its validity in these hybrids'. Conse- 
quently, in elucidating the relations of the forms to each 
other, here as in the preceding family, we have to 
reckon with hybridism as an important factor in the 
modifications of the types. To all appearances the ge- 
nus has its original home in the American seas, where 
Salmon and Charr still occur in masses almost incon- 
ceivable to the European. 
" Smitt, Riksmuseets Salmonidcr , Vet.-Akad. Hand]., Bd. 21, 
h Cf., however, Smitt, 1. c., lab. metr. V and VI, Nos. 371, 
e Cf. Day, British and Irish Salmon idee, pp. 261 and 270, 
cl Day, British and Irish Salmonidce, p. 143. 
e Day, ibid., p. 51. 
From the preceding family we have learnt that 
cross-breeding may take place not only between differ- 
ent species, but also between different genera. Hybri- 
dism alone cannot, therefore, prevent the distinguishing 
of the species. But the variability of form within the 
genus Salmo has hitherto rendered it impossible to de- 
fine with certainty the numerous species that have been 
adopted; and we doubt whether the observer who con- 
sistently requires trustworthy and distinct characters can 
recognise more than three European species of the ge- 
nus: the Salmon, the Huch, and the Charr. As yet, 
however, to the best of our knowledge, only Nilsson 
and Sundevall — the latter in the titles of the figures 
in PI. 58 and 59 in the former edition of “Scandinavian 
Fishes” — have ventured to advance this simple opinion. 
Still, both from a scientific and an economical point 
of view, it is of importance to know the conditions that 
involve the said inconstancy; and to this end it has 
been necessary to denote by special names the more 
or less constant forms that appear under different cir- 
cumstances and in different localities. As regards the 
Salmon, general credence has been given in recent times 
to the opinion first advanced by Lilljeborg and after- 
wards by Widegren, namely that we can distinguish 
between two “species”, the Trout d ( Salmo trutta, Sw. 
grdlaxen ) and the Salmon f! (S. salar , Sw. blanldaxen). 
The same applies in essential points to the Scandinavian 
Charr, among which we can generally distinguish with 
ease two forms, the Northern Charr ( Salmo alpinus , Sw. 
L app lands-rodi ng en) and the Saddling ( S . salvelinus, 
Sw. Vetterns-rodingen). Of the Huch, which, at least 
up to the present, cannot be claimed for the Scandina- 
vian fauna, there are also two forms, the Siberian Huch 
( Salmo fluviatilis ) and the Danube Huch (S. hueJio). 
The Scandinavian forms of the genus Salmo may 
in general be distinguished most readily in the follow- 
ing manner: 
A: Number of scales in a longitudinal row 
above the anal fin, for an extent of V 10 
of the length of the body, at least 23 
(23 — 30). Salmo umbla. 
a: Distance between the ventral fins and 
the tip of the snout more than half 
the length of the body Salmo salvelinus. 
). 8, p. 143. 
386 and 458. 
ig. 52, 2 and 2a. 
