> 
PRESIDENTIAL ADDRESS. 43. 
places, whilst the Alexandrine variety of the latter is com- 
mon near the sea-coasts of the southern parts. 
In Sydney, EL. norvegicus and FE. rattus (including £. 
rattus alexandrinus), are present in about equal numbers. 
Thus, between March Ist, 1904, and December 31st, 1916, 
89,216 of the former and 104,520 of the latter were examin- 
ed in the Microbiological Laboratory of the Department of 
Public Health. In 1904, 1905 and 1906, #. norvegicus was 
more numerous than HL. rattus, in one year being twice as 
many. Since 1907, EF. rattus has been the predominant rat 
submitted for examination, in some years being nearly twice 
as numerous as EL. norvegicus. 
In the ‘‘Report on a Second Outbreak of Plague at 
Sydney, 1902,’’ it is stated, in reference to rats examined 
between 1900 and 1902, that H#. rattus predominated 
amongst those taken along the shores and E. norvegicus 
amonest those taken inland. 
In the Ulmarra district of our North Coast, in 1905, out 
of 1,128 rats examined, only three were EF. rattus. At Graf- 
ton, however, 62 out of 234 were of this species. I have re- 
ceived recently a specimen of EL. rattus from Bathurst, ana 
specimens of both the Alexandrine and of the typical black 
forms from Goulburn. 
Mr. R. H. Cambage informs me that when Stockton and 
Hetton Collieries were working the former contained 
numerous rats but no mice, while in Hetton there were 
multitudes of mice but no rats. He also states from per- 
sonal experience that, in 1891, when on the Upper Nam- 
bucca River, he found, as soon as the lights were ex- 
tinguished, the miners’ huts were invaded every night by 
bush rats, which ran all over the room and over those lying 
in bed. 
From municipal enquiries I am informed that rats are 
known at Hay, and have been seen in the goods yard at 
