378 
STRANGE DWELLINGS . 
wards, and are stuck into a strong, glutinous material of which 
the body of the case is composed, and they look for all the 
world like the spikes of chevciux-de-frise. A web -like skein of 
singularly strong material serves as a rope whereby to swing the 
caddis-case from the branch to which it is attached. And a 
nest more difficult to swallow, and hard to digest, its enemies 
would be rather puzzled to find.’ 
As is frequently the case with such nests, the peculiar form 
serves a double purpose, namely, protection and concealment, 
the sharp points of the thorns performing the former duty, and 
their similarity to surrounding objects the latter. Acacias are 
conspicuous for the thorns with which their branches and some- 
times their trunks are studded, and in several species the 
wooden bayonets are several inches in length, and as large and 
sharp as porcupine quills. These thorns are crowded thickly on 
the branches, and always diverge from each other, so that the 
hand can scarcely be insinuated among the boughs without 
suffering several wounds. The nest being surrounded with 
these thorns, it is evident that all ordinary foes would be baffled 
by such an array of points, no matter how anxious they might 
be to get at the creature within. 
The thorns are equally efficient as a means of concealment, 
for, as they are taken from, the tree itself, they cause the nest to 
harmonise so perfectly with surrounding objects, that it is not 
very easily perceived. 
As long as the caterpillar remains in its larval state, and is 
obliged to feed, it traverses the branches freely, carrying with it 
the prickly home, and bearing the whole of its weight as it 
moves. But when the pupal stage has nearly arrived, the nest is 
suspended to the branch by strong silken threads, and thence- 
forth remains immoveable. 
