934 Transactions. —Z oology- 
for which it is designed. Easily opened by the inmate for all the distance 
which his necessities require, and yet presenting increased resistance to 
every attempt to open it beyond that. 
Spur or stay to the Trap-door. 
There is another appendage to some of the trap-doors, which aids 
materially in the spring with which they shut, or at least prevents them 
from turning right over backwards, or remaining open. It is in reality a 
sort of spur or stay constructed on the outside of the lid close to the hinge, 
and with its thickest edge next the hinge, and it acts as a choke against the 
ground outside the nest when the lid is opened up. This choke is formed 
sometimes of soil, and sometimes of other materials. In one case, No. 11, itis 
evidently formed of several old trap-doors of different sizes, the upper one at 
the top of the choke, and goes to show that when a nest is increased in size, it 
is always enlarged at the mouth, on the side opposite the hinge, and that these 
descriptions of trap-doors are extended somewhat like the growth of a shell, 
always at the lips. This explains the tiled appearance of these trap-doors, 
which has been likened, and very correctly so, to the outside of an oyster 
shell. Or probably it would be more correct to say, that as the old doors 
had, one after the other, become useless through some accident, or through 
the expansion of the mouth of the tube, a new one was constructed below 
the previous one, and joined on to the lining of the tube always at the same 
spot, the hinge. This accounts also for the fact, that such trap-doors 
are generally depressed below the surface of the = at the hinge. 
Bevelled mouth of the Nes 
All the nests found, had the mouth of the ee more or less beveled and 
the lid corresponding, and there were always varying degrees of perfection 
in the workmanship ; some doors fitted exactly to the cup-like form of the 
tube, over which the lining is always extended, so that the lid may fit tight 
down. Others not fitting so exactly, and being a mere flap, covering over 
the mouth of the tube. But in no case was there anything like what 
Moggridge describes and figures, as ‘ cork-nests, with the thick lid going 
down into, and filling up the mouth, so as to require some degree of force 
to take the plug out.” 
Distinctions in the Trap-doors. 
Apart altogether from these variations, and from the oval or circular 
outline, there are two distinctions that may be noticed, in the form of the 
trap-doors, First: Those that are slightly raised above the surrounding 
surface, | at is, in the middle of the lid, and thin off atthe edges; and 
second : those that are flat, and exactly coincident with it, or slightly de- 
pressed. You have now before you twenty-eight specimens of trap-doors, 
and of these, by far the larger number belong to the latter or flat class. 
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