179 
ON THE RECENT DISCOLOURATION OF THE WATERS 
OF PORT JACKSON. 
By Thomas Whitelegge. 
(Plate xxviii.) 
Towards the latter end of last March, the citizens of Sydney 
were astonished and alarmed by the sudden discolouration of the 
water in Port Jackson. The water in the harbour in many 
places presented the appearance of blood, and the Board of Health 
immediately requested Mr. W. M. Hamlet, the Government 
Analyst, to report on the matter. He found that the red colour 
was due to the presence of a minute organism, which he thought 
might be the Englena sanguinea , Ehrenberg. Immediately after 
the publication of this report, quite a number of people gave 
their views of this somewhat mysterious discolouration. It was 
suggested that it was due to zoospores of some marine Algce ; to 
the Trichoclesmium which discolours the Red Sea ; and to the 
young of Medusce ; whilst others maintained that it was caused 
by blood and other refuse turned into the harbour from the 
abattoirs. 
On the 31st March I proceeded to Dawe’s Point and procured 
a bottle full of water, in which there was a good supply of the 
organism in question. After a careful examination I satisfied 
myself that it belonged to the family Peridiniidce , and I published 
a letter in the Daily Telegraph to that effect. At the time I 
thought it was a species of the genus Peridinium , but further 
research led me to the conclusion that it was a new species of 
the closely allied genus Glenodinium ; in the former genus the 
cuirass is marked by the presence of facets, whilst in the latter 
the cuirass is smooth. After the publication of my first letter 
on the subject, I was requested by Dr. E. P. Ramsay, Curator 
of the Museum, to make a detailed examination of the shores 
of the harbour, and to ascertain what effect the organism had 
had on the fauna generally. 
The result of my investigation was embodied in a preliminary 
report furnished to the Department of Fisheries ; this report was 
published in the Sydney daily papers, and also in the “ Records 
of the Australian Museum,” No. 7. During my investigation 
I visited the head of Tarban Creek, Hunter’s Hill on the 
Parramatta River, Mossman’s Bay, Little Sirius Cove, Farm 
Cove, Darling Harbour, Woolloomooloo Bay, Watson's Bay, 
Manly, Coogee, Maroubra, and Middle Harbour. I found the 
organism at all the above-mentioned places in larger or smaller 
A— October, 1891. 
