274 REPORTS FROM THE SECTIONS. 
probably from = water sponges grow ing inthe dams ; amongst 
the diatoms were an iinmense multitude of minute diamond- shaped 
bodies not more than the 2,000th of an inch in extreme length ; 
some with two holes pierced in them near the centre, others 
without. I have been unable to find any thing resembling them 
in any work I have access to; they may probably bea species 
of minute diatom, but whatey er be their nature, they are un- 
doubtedly present in vast numbers in the water supplied to 
i he kno r oe 
and several ie Pleurosigma. The sponge spicules men- 
tioned were ely: in great abundance ; under the ae vag 
oo the head of Fletcher's bay, a small rocky bight ae? of 
Bondi, there is a stream in which I obtained a plentiful supply of 
Synedra Julgens, a long spindle-shaped diatom with coarse trans- 
verse ribbing; the ring was very pur free from 
tifving half of them. I will merely mention Pinnularia major and 
nobilis, besides several other species of this genus, a several 
forms of Navicule i in abundance, and’ Stauroneis of all ki nds, to . 
} ’ 
prepared a few slides for presentation to Ses gentleman who 
wish to have on ne thing I notice in this gathering, that 
amid the multiplicity of other forms the Pleurosi: are con- 
spicuous by their absence; at least, in a hasty search through 
several — I have not been able to find a any. 
arity a seems connected with the Diatomacee in 
i 
the intervention of a waive of another pecies here we seem to 
have a sort of happy family, ahich, though picarer ced to those 
who seek variety on their slides, i is rather puzzling to the collector 
les wishes per tosuit 
he conditions required on the perfect display of any given diatom- 
