PRESIDENTIAL ADDRESS. 109 
had forwarded a collection of ecto-parasites from rats to the 
Hon. N. Charles Rothschild. The host animals were caught 
near the banks of the R. Torrens, which runs through Ade- 
laide, its water being dammed back to form an artificial 
lake called ‘‘ Torrens Lake.’’ Amongst these external para-— 
sites were fleas from common rats and lice from a water- 
rat, Hydromys leucogaster. Presumably this was the source 
of the specimens described by Neumann, the host having 
been wrongly noted, and Torrens ‘‘Lake’’ being referred to 
as ‘‘lac Torrens.’’ As further support to this view, Dr. 
Johnston later examined a pediculid found by us on H. leu- 
cogaster caught in Sydney Harbour. The insect was muti- 
lated, but its appearance suggested that it was the species 
described by Neumann. 
AcsarIna: Leiognathus bacotr Hirst.—On several occasions 
in Sydney complaints have been received of small mites at- 
tacking workers in factories and shops. A similar com- 
plaint was received from Fremantle, in Western Australia, 
in 1908, in the case of men working on the wharves at night. 
These mites cause a good deal of irritation and skin- 
scratching. Enquiries showed the association with their 
presence of rats, some of which were caught, infested with 
the mites, in a shop in Sydney, next door to one of these 
factories. The mites were sent for identification to Mr. S. 
Hirst, of the British Museum, who identified them as Letog- 
nathus bacotr Hirst, a species originally described by him 
from Mus norvegicus, and found in Egypt, Abyssinia, Aus- 
tralia and South America. The irritation caused by these 
mites is very similar to that caused by Leiognathus bursa 
Perlese = L. morsitans Hirst, which has been identified for 
us also by Mr. Hirst, and is usually conveyed in Sydney by 
starlings nesting in premises. This other mite is normally 
a parasite of domestic poultry in the more tropical parts 
of the world. 
