PRESIDENTIAL ADDRESS. 135 
D. Le Souef! quotes newspaper extracts showing the 
presence of an extensive visitation of mice in 1905 in the 
Merriwa and Mitiama districts, Victoria. 
From these accounts, it seems highly probable that the 
1903-5 visitation was due, like the 1917 one, to the common 
house-mouse, Mus musculus. I, am unaware of any actual 
accurate determination of the species, but Mr. Gavel states 
clearly that they resembled in every way the house mouse, 
and that he had no doubt that they were this species, whilst 
Mr. Le‘Souef, who reeeived Victorian specimens, says they 
were apparently the ordinary domestic mouse. Their 
habits conformed with those of Mus musculus, and their 
behaviour was very similar to that of the mice of the recent 
visitation which have been so identified. Mr. Cameron 
raises a doubt, however, by referring to a marked variation 
in size, and to the presence of variation in colour. Amongst 
large numbers of mice, partial or complete albinism and 
other colour changes, including melanism, might occasion- 
ally be expected, due to developmental deficiencies of the 
factors responsible for colour production, or perhaps to 
mutations of a positive’ nature. Occasional instances of 
partial albinism have been noted in the recent visitation, 
but I have not heard of unusual differences in the size of 
adult mice. 
Mice in South Australia in 1911.—In a MSS. letter, 
Dr. R. H. Pulleine mentions that mice (M. musculus) in this 
year constituted a ‘‘severe plague’’ in Northern South Aus- 
tralia. 
The Mouse Plague of 1917. 
It appears that the first indication of mice being more 
numerous than usual was noticed in New South Wales in 
December, 1916, but in that State the mice had not increased 
‘“‘to an alarming extent’’ until early in April, 1917, when 
tLe Souef, Wild Life in Australia, p. 132. 
