896 
SCANDINAVIAN FISHES. 
The ventral tins are broader and truncate, and their 
average length is about 14 1 / 2 — 13 % of that of the body. 
The distance between the latter tins and the tip of the 
snout is on an average about 47 %, the preabdominal 
length about 28 %, and the postabdominal length about 
24 %, of the length of the body. 
The scales of the body we have already noticed. 
Only the head and the fins are naked. The lateral line 
runs from the temples along the posttemporal bone on 
each side, descending at the top of the gill-opening, 
but its backward course on the sides of the body is 
almost perfectly straight, with only a slight downward 
curve at the extreme front. 
The coloration is green, shading into steel-blue, on 
the back, silvery white on the sides, of a more or less 
pure milk-white on the belly. The back, as well as 
the occiput and snout, is slightly transparent, but far 
less than in the Smelt. The tip of the snout and the 
point of the lower jaw are usually coloured with a black 
pigment, which extends in a thinner coat to the maxil- 
laries and to the margin of the follicle of each scale 
on the body. The gill-covers commonly gleam with a 
brassy lustre, especially at the top. The adipose tin is 
of the same colour as the back. The dorsal and caudal 
tins are of a more or less dark gray, the other tins 
light and transparent. The iris is silvery white, the 
eyeball coal-black at the top. 
The Vendace is really a Baltic fish, with the centre 
of its range in the Baltic Sea and the* lakes of the 
countries — principally the eastern ones — bordering on 
the Baltic. But, if modern opinions as to the specific 
determination be correct, it also occurs in Scotland, to 
which country, says tradition, it has been introduced 
from abroad. The Irish lakes (Loughs Neagh, Erne, 
Derg, and Corrib) contain a form, Coregonus pollan, so 
closely resembling the Vendace that the specific distinc- 
tion between them can hardly lie maintained. The Pol- 
lan as a rule has fewer gill-rakers (34 — 38 on the front 
of the first branchial arch) and fewer anal rays (12 — 
13). At an earlier age than the other Vendaces the 
Pollan approaches in the depth of the snout the pro- 
portions which we have already remarked as most cha- 
racteristic of the true Gwyniads". The most distinctive 
character of the Pollan, however, is the short base of 
the anal tin, which measures at most about 3 /n of the 
length of the body, and is so short that the least depth 
of the tail is at least 3 / 4 thereof. In this respect, as in 
many others, the Pollan composes one extreme in the 
form-series of the Vendaces (the albula group), the op- 
posite extreme consisting of the Siberian Seldetkan or 
Coregonus Merkii. Strangely enough, this difference in 
form within the Vendace group answers to the diffe- 
rence we have above observed between the Salmons of 
the Atlantic and Pacific basins. The Oncorhynchus 
group of the Pacific differs from the Salmo group of 
the Atlantic mainly in the greater length of its anal 
fin; and the nearer the range of the albula group ap- 
proaches to the Pacific, the longer is the base of its anal 
fin. We find the following average relations between 
the length of the base of the anal fin and that of the 
head reduced: 
Average 
Pollan. 
Albula. 
Vimha. 
Seldetkan. 
Length of the base of the anal fin express- 
[ ed in % of that of the head reduced 
62.5 
73.9 
82.5 
90.3 
These averages can hardly be the expression of a mere 
accident, for they are attended with similar results in 
several other relations; and there is thus a distinct 
connexion here between the difference in form and the 
geographical separation. Even in Scandinavia the true 
albula and the virnba show some geographical separation, 
the former being commonest to the extreme north and 
in Lake Wetter, the latter in the Malar vallev and the 
basin of Lake Wener; but our most typical specimens 
of virnba are from Finland. These two forms are be- 
sides different, as we have seen above, in most of the 
average proportions ; but the changes of growth and the 
sexual distinctions reduce the differences to such an 
extent that constant characters can hardly be adduced. 
The Vendace occurs in all the provinces of Sweden, 
except Gothland, Blekinge, Halland, and BohuslarP. 
From Norway it was described and figured even by 
Ascanius, but it is found only in Lake Mjosen and 
some of the small lakes to the extreme south-east. In 
Finland it is as common as in Sweden, up to about the 
69th degree of latitude. In the Arctic Ocean it is 
wanting; but from Western Russia and the Baltic Pro- 
vinces its range extends over North Germany to Hol- 
“ Smitt, Riksmuseets Salmonider , p. 233. 
6 Cf. Under cl. Bet. Forsl. Ny Fislceristadga 1883, p. 159. 
