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LEPIDOPTERA. — RHOPALOCERA. 337 
are suspended head downwards in the pupa state, and which have to 
ascend the slight exuviee of the chrysalis case; whilst the hexapod 
butterflies, being girt so as to lie in a horizontal position, have only to 
creep out of their case. Some exceptions occur against this rule, 
as in the case of the gregarious Mexican butterfly, described by me 
under the name of Eucheira socialis (Trans. Ent. Soc. vol. i. pl. 6.), 
which, although simply suspended by the tail in the chrysalis state, is 
provided with perfect fore legs. The Libythiz also, which have sus- 
pended pupe, are also furnished, at least in the females, with six feet. 
The Peridromides, on the other hand, have the chrysalides girt, and 
yet they possess only four perfect feet. 
The pupz of many butterflies belonging to the families Helico- 
niidz and Nymphalide are ornamented with golden spots, whence 
they were termed Aureliz, or chrysalides. This appearance was 
seized upon by the alchemists in support of their doctrines ; but 
Réaumur in France, and Lister and Ray in England, clearly proved 
that it originated in the shining white membrane seen through the 
very slender and transparent outer skin. It is requisite also, for the 
preservation of this appearance, that the inner membrane be moist, 
and hence the gilding disappears when the absorption of the fluids 
has been effected by the inclosed insect’s approach to perfection. 
Ray has related various experiments upon this subject in his Leéters. 
(Edited by Derham, pp. 82. 86. 88. 90.) 
Some species of these insects have afforded materials to several 
entomotomists for the production of elaborate memoirs upon their 
anatomy. Swammerdam, especially (in his History of Insects), in- 
vestigated that of the great cabbage butterfly, and the tortoiseshell 
butterfly of the nettle. Herold, also, in his Entwickelungs. der 
Schmettertinge, has also studied the former species, especially tracing 
the variations which its internal organs undergo during the process of 
transformation. 
Linnzus divided the genus Papilio into five principal groups. 
A. Equites. — Having the fore wings longer from the posterior angle to the apex 
than to the base; subdivided into Troes (Trojans), haying red spots on the 
breast, and Achivi (Greeks), having no such spots. 
B. Heliconii. — Wings narrow, entire, often almost naked. 
C. Danai. — Wings entire ; subdivided into Candidi, with white wings, and Fes- 
tivi, with variegated wings. 
D. Nymphales. — Wings dentated; subdivided into Ocellati, or those with eye-like 
. spots, and Phalerati, or those with simple spots. 
VOL. II. Z 
