PISCES. 
137 
Cobitis tgenia, Petromyzon planeri, and perhaps also 
Gobio fluviatilis and AspiuS Papax are also of Russian origin. 
7 . The other 32 species are of Scandinavian origin. 
c. The marine species of the Baltic coasts are 21 in number. 
a. 11 belong to the fauna of the German Ocean^ viz. 
Cottus bubalis, Spinachia vulgaris, Gobius niger, Gobius minu- 
tus, Rhombus maximus, Ammodytes lanceolatus, B clone vul- 
garis, Clupea sprattus, Siphostoma typhle, Nerophis ophidion, 
and Acipenser sturio. All these fishes are of comparatively rare 
occm’rence on the Finnish shores of the Baltic, where they do 
not propagate their species ; so that only large individuals are 
met with. Therefore the author concludes that the individuals 
of these species have migrated eastwards from the Baltic. 
The 10 others are common to the Baltic and the 
Glacial Ocean, viz. Cottus scorpius, Cottus quadricornis, Cy- 
clopterus lumpus, Liparis barbatus, Centronotus gunellus, 
Zoarces viviparus, Platessa flesus, Gadus morrhua, Clupea ha- 
rengus var. membras, and Petromyzon marinus. Some of them 
are very common to the extremities of the Bothnian and Finnian 
Gulfs ; they propagate their species, and agree with their fore- 
fathers in the Glacial Ocean in every point, but remain com- 
paratively smaller, leaner, almost starved. Especially three of 
them — Cottus quadricornis, Liparis barhatus, and Clujjea ha- 
rengus var. membras — deserve particular attention ; they are 
limited to the northern parts of the Baltic only, and entirely 
absent in the southern portions and on the western coasts of 
Scandinavia. Therefore nobody will suppose that they have 
come into the Baltic through the Sound. How, then, is the pre- 
sence of these arctic fishes in the Bothnian Gulf to be explained ? 
Prof. S. Loven has lately shown that several small animals of 
marine origin are found in the great lakes of Sweden and Fin- 
land, and in the Baltic. They have never been met with in the 
German and Atlantic Oceans, but several of them (Idothea 
entomon, Gammarus loricatus, tialicfyptus spinulosus, and 
Polynoe sarsi) are found again in the coldest parts of the Glacial 
Ocean, these arctic representatives being more developed than 
the southern ones. Prof. Loven explains the presence of these 
animals in Scandinavia by the great depth of the freshwater 
lakes, and by the former continuity of the Baltic with the 
Glacial Ocean. Diuing the second half of the Glacial period 
the greater part of Finland and of the middle of Sweden were' 
submerged, and the Baltic was a great gulf of the Glacial Ocean 
and not connected with the German Ocean. By the gradual 
elevation of the Scandinavian continent, the Baltic became dis- 
connected from the Glacial Ocean, and the great lakes separated 
from the Baltic. In consequence of the gradual change of the 
salt water into fresh, the marine fauna became gradually extinct, 
with the exception of the glacial forms mentioned above. 
