1864. | Zoology and Physiology. 513 
experiments on animals and on man, it is concluded that the cerebel- 
lum isa source of voluntary power to the muscles supplied by the 
spinal nerves. It influences the lower more than the upper limbs, and 
produces habitual rather than impulsive movements—and it has a 
power, which has been described as that of co-ordination—and it is 
suggested that the outer portion of the organs may be the source of 
its voluntary motive power, while its inner layer is the means of 
regulating its distribution. 
Mr. Rowley, of Brighton, has recently added to his collection the 
only egg of the Atpyornis maximus which ever came to this country, 
and has in a shilling pamphlet, published by Tribner and Co. (and 
noticed amongst our reviews), made some interesting observations, not 
only on the unique zoological specimen, but upon the bird which 
laid it. 
G. O. Sars, son of the celebrated Norwegian Professor, has been 
dredging in freshwater lakes in Norway, and has met with some curious 
confirmations of former observations, that true imhabitants of the sea 
can, under certain circumstances, gradually accustom themselves to 
live in thoroughly fresh water. The conditions of change, as exhibited 
in some Swedish lakes to Professor Lovén, may be very gradual, 
operating throughout thousands of years, but, in the present instance, 
it must liave been much shorter. Sars found in the mud at the bottom 
of this lale a small red crustacean, in which he at once recognized a 
saltwater species, although the water was perfectly fresh and pleasant 
to the taste. In the case of this lake, apparently some very high flood, 
or a furious storm from the west, has driven the sea up on some occa- 
sion into the loch, which lies close to the coast. Their residence in a 
foreign medium, however, appeared to have changed the mode of life 
of these animals, for, instead of being found as usual in the shallowest 
pools, they were here in the deepest part of the water, sunk in the mud. 
Dredging in Mjésen Lake, which flows through a large river, he dis- 
covered a crustacean, Mysis relicta, of Lovén, belonging exclusively to 
salt-water ; one of those extraordinary relics of the glacial period, whose 
presence in some of the great inland lakes of Sweden has lately excited 
so much interest. Associated with it were numerous examples of a 
Gammarus (G. cancelloides), first discovered in the seas of Baikal and 
Angora, and which has lately also been found in Sweden, and which 
Lovén considers originally to have belonged to the sea. 
These observations of Lovén and Sars may tend to modify mate- 
rially certain geological theories. 
A valuable and interesting paper has been communicated to the 
Linnean Society by Mr. A. R. Wallace, on the ‘ Phenomena of Varia- 
tion and Geographical Distribution as exhibited by the Malayan 
Papilionide.’ The large butterflies of this region are well adapted 
for this purpose, since their gaily-painted wings register the minutest 
changes of organization, and exhibit on an enlarged scale the effects of 
the climatal and organic conditions which have influenced more or 
less profoundly the organization of every living being. The variations 
occurring among the 120 species inhabiting the Malayan Archipelago 
are classed by Mr. Wallace under the heads of, 1st, simple variability ; 
