28 RUDOLF SÖDERBERG, STUD1ES OF THE BIRDS IN NORTH WEST AUSTRALIA. 
It is evident, however, that not only does the hanging type of nest originate 
from a highly developed art of nest-building, but also that the other, the »fixed> 
form of nest, has been developed to such an extent that in many cases it may, in 
its ingenuity, be compared with the former. 
Among the latter kind I omit many very remarkable ones (for instance the 
nest of Pseudogerygone), and specially mention some, in which mimicry shows a per- 
fection that has not been reached by any species of Passeriformes in the North. 
Here it is of interest to call attention to the fact that we are dealing with 
nests, which, because of their situation at the trunks of the bushes or the thicker 
Fig. 12. Nest of Neositta pileata, Fig. 13. Nest of Neositta chrysoptera, 
Museum in Perth. Museum in Perth. 
branches, are still more exposed to egg-plundering enemies than the hanging nests. 
Their need of a protective disguise is thus evident, and a natural consequence of 
this is that it is among these species that skill in carefully concealing their nests 
reaches its highest point. 
First may be mentioned a discovery of a nest of Neosilta pileata (Sunday Is- 
land '"/2 1911). It was found in a narrow Eucalyptus tree, high up beside the trunk. 
The nest was, on account of both its colour as well as its shape, fitted in a high 
degree to escape attention. It was extended along the trunk of the tree so that it 
projected as a protuberance, and the inner part of the nest did not extend to quite 
a third part of the whole length of the nest. Outside it had a protective material 
of bark chips, which were put on so that they imitated the vertical streaks of the 
bark of the tree. 
