304 : Transactions,— Zoology. 
part of the lid on the under side is protuberant, as shown in fig. 7, at the 
part that is unhinged, and it is there the lid is thickest. There is, too, an 
indent into the side of the lip of the nest opposite this protuberance on the 
lid, and into which it fits as shown in fig. 8 (which represents mouth of 
nest with the door off) causing the lid, when shut down, to lock, as it were, 
like a dove-tail, so that in order to open it again you have to insert a knife 
` between the trap-door and the mouth of the nest. This trap-door with its 
hinges, locking apparatus, and counter-sinking is, I think, one of the most 
marvellous mechanical arrangements that I have ever come across in 
nature. Noone can attentively examine this ingenious contrivance without 
being impressed with the fact that here in one of what we are accustomed 
to call the lowest class of animals, we have something wondrously akin to 
the inventive faculty in man. But this paper is one of facts and not specu- 
lations, and so I must forbear. As in the previous instance there is no 
spring in the hinges, so that the trap-door remains open when left open. 
Though the outside appearance of the trap-door represents the segment of 
an oval, still the contour of the hole inside below the counter-sinking is 
nearly circular as shown in fig. 8. 
Nos. 3 and 4.—The other two Californian nests are in the same character 
of ground as the preceding, and are of the same shape, and have the same 
description of hinge as No. 1, only they are both of smaller size. They are 
both thickened on the under side and bevelled on the edges like the others. 
No. 8 though hinged across has a protuberance slightly developed on the 
under side of the lid in the centre of the hinge area the same as No. 2, 
suggesting the idea that possibly the two hinges in that nest may have been 
caused by the locking effect of the protuberance as it is increased in size, 
but there is no evidence of unfinished or wraggled edges in No. 2 indicative 
of the separation having been effected by such a wearing process. On the 
under side of the lid of No. 4 on the free edge there are two distinct holes 
or claw marks exactly in front, but they do not penetrate through the lid. 
Both nests are lined with very tough web, are tortuous, but have no 
enlargement. 
Nests from Western Australia. 
These two nests (which were presented by His Excellency Governor 
Weld) differ entirely from the Californian. They are raised above the surface 
of the ground, and the lid fits on to the mouth of the nest like a cap, 
overlaps somewhat all round, and is thickened entirely on the outside. 
They are also smaller in size than the Californian. : 
Nest No. 1 is almost circular (fig. 9: a trap-door closed; b small nest 
without lid); across the mouth outside it measures six-tenths of an inch, . 
. whilst the lid fitting over it measures seven-tenths ; across the mouth inside 
ie eed 
