326 
ARTHUR DENDY. 
a small pea, embedded in the choanosome. I picked out a 
number of these embryos from the living Sponge and placed 
them directly in strong spirit, and also preserved portions of 
the mother Sponge in the same way. This simple method of 
preservation, adopted at the time for want of other reagents, 
subsequently proved to have been highly successful. 
After cutting sections of the embryos and finding that they 
presented certain very remarkable features, I determined to 
make a complete study of the anatomy of the adult Sponge. 
Fortunately, I found amongst a splendid collection of well- 
preserved Sponges already sent up to the Melbourne University 
by Mr. Wilson, several more specimens of Stelospongus 
flabellifor mis, and I thus had abundance of material at 
my disposal. 
My preparations were stained with borax carmine and cut in 
paraffin in the usual manner, and I found that in order to 
ensure success it was very important not to allow the tem- 
perature of the paraffin to rise above 128° F. Probably a 
lower temperature would have been better still, but unfortu- 
nately I had only hard paraffin to work with. 
With regard to the figures, I may state that while some of 
them are more or less diagrammatic, all are taken from actual 
preparations, either individual or combined, with the exception 
of figs. 9 and 10, which are pure diagrams. 
I have very great pleasure in taking this opportunity of ex- 
pressing my sincere thanks to Mr. Bracebridge Wilson, to 
whom I am indebted for the whole of my material, and to 
Professor W. B. Spencer, who, throughout the progress of the 
work, has given me much valuable advice. 
Anatomy and Histology. 
External Characters. 
An idea of the general appearance and size of the Sponge may 
be gained from fig. 1, which represents a fairly typical specimen, 
from which a portion has been cut off, drawn of the natural 
