147 
numbers as to literally clog the gills and prevent respiration, or 
the water may have been so deficient in oxygen as to be unfit to 
support the higher forms of life, or they may have been so overfed 
as to produce indigestiou and sickness. No doubt any one of 
these causes acting for weeks in succession, or a combination of 
the whole, would be sufficient to render the entire littoral fauna 
unhealthy ; and every death of the larger animals would tend to 
make the conditions worse for those that remained. I examined 
the stomachs of both oysters and mussels, and found them full of 
Peridinia, and in many cases the water enclosed in the shell 
contained great quantities in a living condition. 
From what I have observed of the habits of the particular 
species of the Peridinia in question they appear to be extremely 
social, and seek each other, and swim in lines or clouds, always 
with a tendancy towards the light ; and, as it is probable they do 
not extend to a great depth, the bottom fauna will not be so much 
affected as the littoral. The sudden appearance of this organism, 
which has discoloured the whole of the waters of Port Jackson 
and destroyed a very considerable portion of its fauna, is another 
instance of our ignorance of the various conditions which affect 
our marine food supplies, and shows the importance and necessity 
of the immediate establishment of a thoroughly efficient biological 
station. Tf such an Institution had been in existence during the 
presence of this extraordinary visitation, the whole of the question 
as to its effects on our marine fauna could have been satisfactorily 
determined experimental ly . 
I have the honour to be, Sir, your obedient servant, 
Thomas Whitelegge. 
P.S. — (7th May) The Peridinium mentioned in the above 
report is probably a new species, and will be dealt with in a 
further report. The organism in question made its appearance 
in vast numbers about the middle of March, and is now 
disappearing. — T. W . 
NOTE ON THE NIDIFICATION OF PLOWS NOVjE- 
HOLLANDIJ Gould. 
The New Holland Snake-bird or Darter. 
By A. J. North, F.L.S. 
The Trustees of the Australian Museum have lately received the 
eggs of P lotus uoV(£-lcollandi(£ : taken by Mr. J. L. Ayres at Lake 
