22 PRESIDENTIAL ADDRESS. 
The Geological Survey is now publishing not only 
routine and economic work, such as mining reports, but 
also purely scientific work. 
A recent memoir, which was issued at the end of 1915, 
contains a report on our Mesozoic flora by our Hon. Sec- 
retary, Mr. Walkom, who is still engaged in its study ; 
whilst one just issued contains Mr. R. J. Tillyard’s account 
of the Mesozoic and Tertiary insect remains discovered 
by the Government Geologist, Mr. Dunstan. 
The members of the staff of the Australian Institute 
of Tropical Medicine, Townsville, North Queensland, are 
continuing their investigations in regard to disease, parasites, 
mosquitoes, biting flies, etc., a number of reports having 
appeared in various publications during the year. 
Before concluding this, the first portion of my address, 
I think it appropriate that I should refer to recent work 
regarding two biological problems of outstanding import- 
ance to this State, viz., the eradication of prickly pear 
and the control of the parasite, Onchocerca gibsoni, Cleland 
and Johnston, which produces ‘‘ worm-nodules”’ or 
‘* worm-nests ’’ (worm fibromata) in such a large percentage 
of our cattle and thereby causes great loss to the meat 
producing industry. As you are aware, I have been actively 
interested in both of these matters. 
TH® ERADICATION OF PRICKLY PEAR. 
The various species of prickly pear, Opuntia spp., 
cover huge tracts of territory in this State as well as in 
New South Wales. The most important, because the 
most abundant, is the common pest pear Opuntia inermis 
var., and its more spiny variety (or perhaps related species) 
which we may term the Burnett Prickly Pear, as it is 
particularly prevalent in certain portions of the valley 
of that river, though it occurs also elsewhere in this State. 
Probably the most widely distributed species in Australia 
is O. monacantha. 
Some years ago the Queensland Government estab- 
lished an experimental station at Dulacca, in the heart 
of one of the infested districts and placed it under the 
control of one of our members, Dr. Jean White-Haney, 
