8 Mr. J. O. Westwood on a Species of Butterfly. 
P. S. Since the preceding memoir was read, the two following 
notices, subsequently published, have been observed, which, in 
some respects, illustrate the habits of the insects in question. 
M. Lacordaire {Ann. Soc. Ent. de France, 1833, p. 385) states 
that the larvae of Papilio Archelaus live in societies, consisting of 
100, 150, or 200 individuals, the community residing when very 
young upon a single leaf, arranged side by side, with the heads 
turned in the same direction. When one is touched, they all simul- 
taneously raise their heads, moving them about in all directions, and 
at the same time renew their quiet position. When arrived at a 
more mature growth, they are found in the same position upon the 
trunk of the tree. 
The other notice relates to Saturnia Prometliea, a fine North 
American species, and is very analogous to the account of the 
proceedings of the Thecla Isocrates, given above. Mr. Titian 
Peale, to whom I am indebted for an extensive collection of 
North American insects, has given an interesting account of the 
habits of the Saturnia Prometliea, in his valuable work, entitled 
Lepidoptera Americana, stating that its caterpillar, when full grown, 
selects a perfect leaf of the swamp button wood ( Ceplialanthus 
Occidentals , upon which it feeds), the upper surface of which it 
covers with a fine light yellowish brown silk, extending this coating 
with great skill and foresight over the footstalk of the leaf, and at- 
taching it firmly to the branch so as to secure the leaf from being 
separated by any accident. This preliminary object having been 
accomplished, the caterpillar next draws the edges of the leaf 
together, thus forming a perfect external covering or mantle, in 
which it spins a fine strong and durable cocoon of fine silk, in 
which it assumes the pupa state. At first, the leaf enveloping the 
cocoon remains green, but soon changes to a red or brown colour, 
when it becomes brittle, and is gradually carried away by the 
winds and storms of the winter, until finally nothing remains except 
the cocoon itself, which is firmly suspended by the silk which once 
covered the footstalk of the leaf. This defence, it will however 
be perceived, cannot be considered as so firm and complete as that 
prepared by the pomegranate butterfly. 
