0)1 the Pi-esence and Structure of a Strldulating Organ in 
Phlogius (Phrictus) crassipes. 
By BALDWIN SPENCER, M.A., 
Professor of Biology in the University of Melbourne. 
(Plate 28). 
During the Expedition we were frequently told of the existence of a spider 
which made a booming or barking noise at night time. The white settlers, as well 
as many of the aborigines, firmly believed that such a spider actually existed, in 
fact it goes by the name of the Barking Spider. At Alice Springs for the first 
time we secured specimens of it. It turned out to be Phlogius {Fh?ictus) crassipes, 
a large foinn belonging to the tribe Territelarite. It lives in burrows in hard 
ground ; on the surface is a hole perhaps an inch in diameter leading into the 
burrow, which goes down in a slightly slanting direction to the depth of a foot and 
a half or even more, where it ends in a more or less spherical space about two 
inches in diameter, in which during the daytime the spider lies. In this chamber 
wei’e remains of beetles and small portions of web. All the specimens secured, 
both here and elsewhere, as at Charlotte Waters, were females. 
Whilst staying at Alice Springs I had the opportunity of watching the animal 
alive, and kept several in this state for nearly two weeks to try and find out if it 
really made the noise attributed to it, and if so how it was made. Thinking it 
possible that the noise might be intensified by the form of the burrow, supposing, 
what was scarcely likely, that it produced the sound underground, I put one or 
two into tubular structures with a hollow space containing sand at the bottom. 
At night we used to go and sit not far away from where the animals were actually 
living in their burrows, but there was no sound of any kind to be heard. This 
was attributed to the fact that the sound is usually made during and after the wet 
season, which is in itself significant, as that is the time when birds of all kinds are 
about. 
The evidence in favour of the barking or booming being produced by the 
spiders consisted apparently in the fact that it had been heard at night, and that 
on going to the spot from which the sound proceeded next day spider burrows 
containing the live animal had been found. I spent a night out in the scrub with 
a friend, and we heard the noise attributed to the spider ; but in this case, as we 
