DEC 2 1891 



1T9 



ON THE RECENT DISCOLOURATION OF THE WATERS 

 OF PORT JACKSON. 



i3Y 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 Trichodesmium which discolours the Red Sea ; and to the 

 young of Medusm ; 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 Peridinuim, but further 

 research led me to the conclusion that it was a new species of 

 the closely allied genus Glenodininm ; 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, 1861. 



