Prof. Milne — Across Enrope and Asia. 567 
fluviatilis, Salmo coregonoides, a Cottus, and Thymallus are also found 
in the lake. 
Besides the seal, called by some Phoca Baicalensis, and the omool, 
which may be regarded as being so far peculiar to the lake, Cor eg onus 
Baicalensis, Squalidus Baikalensis, and Calorrhous Baikalensis, along 
with other creatnres, are also peculiar. 
There are also many Crnstaceans which have hitherto been only 
found in the Baikal. Amongst these there are, I think, seventy or 
more species of Gammarus. These latter, many of which I saw, are 
generally of a light yellow colour. They live in holes in the sand 
or clay. They are very ravenous. If a dead body is sunk in the 
lake, the whole of the flesh is devoured in a few days, and only a 
skeleton remains. It was by lowering a carcase like that of a sheep 
into the lake, and by taking advantage of the flesh-eating tendency 
of these creatures, that many new species were captured. Osteo- 
logical specimens have been prepared by sinking them for a few 
days in the lake. This was very satisfactory, as the whole of the 
flesh was removed without any attack being made upon the outer 
portion of the bone, as ants are very apt to do. 
Some of these. like G. verrucosus, G. viridis, and G. cancellatus, live 
near the shore in shallow water, whilst others appear to only in- 
habit the deeper portions of the lake. In addition to the Crustaceans, 
Lake Baikal yields a peculiar series of Mollusca. 
Some interesting experiments have been made here by M. 
Debovsky as to the depth at. which these creatures can exist. 
One of these experiments was to place living specimens of Paludina 
Baicalensis and Choanomphalus Mackii in a bag and sink them to 
vai’ious depths between 700 and 1200 feet, and there allow them 
to remain for several weeks. The result of this was that the sub- 
jects survived in an apparently healthy condition. 
Some Crustaceans, similar to those in the Baikal, have been found 
in a small lake up the Tunka Valley, and I have already mentioned 
that it is not at all unlikely that seals also occur in neighbouring 
lakes. 
These facts, small as they are, naturally tend to the surmise that 
the fauna of the inland fresh waters of these districts may, on ex- 
amination, prove to have a great similarity. Should this be so, we 
may perhaps be led to think, as has before been suggested, that 
all the small lakes which we see dotted on the map around the 
Baikal were once connected, and in former times existed as a vast 
inland sea. That the Baikal was once more extensive than it is at 
present seems to be indicated in the terraces which appear to be 
marked upon its Southern boundaries. Still farther to the south and 
south-east, up the valley of the Tunka, Mr. Tchersky teils me that 
there are beds of alluvium marking an old extension of the lake. 
So far as I could learn, there appear to have been two well- 
marked periods in the history of this lake : first there was the 
original cutting out of the rocky bed, and a subsequent filling in 
with alluvium, and secondly there was the cutting out of the basin 
in the alluvium, traces of which remain in the valley of the Tunka, 
