218 THE AUSTRALIAN NATURALIST, 
under the lead of the President, Mr. A. A. Hamilton, who 
has kindly written a note on the special characteristics of 
the flora. 
The remainder of the party spent the day searching 
the creek for aquatic specimens. We are greatly indebted 
to Mr. R. J. Tillyard, M.A., B.Se., for his kindness in 
identifying the specimens. 
Many larvae were obtained by diligent dredging of 
the water-weeds, and these were carefully examined alive 
in a shallow white dish full of water. The larvae of the 
dragonfly, Lestes cingwatus, were found in various stages 
of development, and in some the budding wings were 
clearly visible. The fine caudal gills of this genus were 
pointed out. Shrimps were obtained in abundance, and 
their digestive tract could be plainly seen with the naked 
eye; but best worth watching was their very beautiful gill 
system. The whirligig’ beetle, Macrogyra, and the water- 
boatman, Notanecta, were both found on the weeds. 
An abundant fauna was discovered on the under sur- 
faces of submerged flat rocks. The small conical cases of 
the caddis larva, Helicopsyche, were seen to be built of 
fine sand grains; whilst the green transparent pupa of 
Hydropsyche was found hidden amongst the little mound 
of pebbles flrmly secured to the rock which serves as a 
shelter from the larva of this genus. The active larvae 
of the mayfly, Atalophlebia, proved most interesting when — 
examined with a lens in a bright light, the rapid rhythmic 
motion of their gills being specially fascinating. Several 
interesting dragonfly larvae were collected, including Ats- 
trocordulia refracta, Aeschna brevistyla, Hemigomphus 
heteroclitus; the latter were obtained by careful searching 
of the clean sand of the creek bed, whilst the Aeschna 
larvae were best obtained by dredging the vegetable debris. 
The larger dragonfly larvae were put into a dish, 
with a little fine mud amongst the water. This served 
to detect the current of water, which is ejected from the 
rectum with sufficient momentum to cause the forward 
propulsion of the larvae. In such cases the gills are in- 
ternal, and line the walls of the rectum; they absorb the 
oxygen from the water before it is ejected. The more 
rapid the swimming movement the more abundant is the 
