290 SMITHSONIAN MISCELLANEOUS COLLECTIONS [voL. 48 
with R, and R,,,, as is also a similar appearance in the adult wing 
of Tascina orientalis. This discovery of a split-back condition of 
R,,; in Papilio and Vanessa has passed unnoticed by later workers. 
Although these vestiges in three forms of Rhopalocera (Anosia, 
Papilio, and Vanessa) should certainly be interpreted as evidence of 
a split-back condition of the vein R,,,, it was necessary that pupal 
conditions in other groups should be investigated before the same 
interpretation could be applied to similar structures in them. Ac- 
cordingly I have removed, mounted, and photographed pupal wings 
of Epargyreus tityrus, Anosia plexippus, Papilio polyxenes, Euva- 
nessa antiopa, Basilarchia archippus, Vanessa cardut, Pieris rape, and 
Femseca tarquimius (pls. LX1, LXI, figs. 17, 21, 25,27, 29, and Lx, fig. 
1). In the first six, radius showed very clearly this split-back condi- 
tion but, although all stages from the mature caterpillar to the adult 
butterfly were examined, the last two showed a four-branched radial 
trachea in which there was no evidence of any such modification. 
The choice of Pieris rape as a representative of the Pieridze was 
unfortunate, for all traces of this splitting back of R,,, have dis- 
appeared from both pupal and adult wings, while the adult wings of 
Eurymus philodice and Anthocharis sara show these traces very well 
preserved and it is therefore very probable that, had their pupz been 
examined, the split-back condition of R,,. would have been found 
(pl. Lx1, figs. 31 and 32). On the other hand, Femiseca was prob- 
ably as good a type as the North American Lycznidz could furnish, 
for the vein reduction has proceeded to such an extent in this family 
that very few of its members retain any traces of this modification. 
The forms in my possession which do retain such traces come from 
South America and southern Asia (pl. Lx11, fig. 33). 
The wide occurrence of these vestiges, which are clearly remnants 
of a split-back condition of the vein R,,,, renders entirely justifiable 
the interpretation of similar structures in related forms as homo- 
logous and signifying the same condition. ‘These vestiges occur in 
all families and in the following examples they are especially well 
marked: Epargyreus tityrus of the Hesperide; Papilio polyxenes of 
the Papilionide; Parnassius smitheus of the Parnasside; Hypatus 
bachmani of the Libytheide; Anosia plexippus of the Danaide; 
Leucothyris quinatina of the Neotropide; Apostraphia charithonia of 
the Heliconide ; Semnopsyche diana and Euphydryas phaeton of the 
Nymphalide; Catoblepia sp. of the Brassolide; Morpho sp. of the 
Morphide ; Erebia tyndarus of the Satyridz ; Anthocharis sara of the 
Pieride ; Arhopala hercules of the Lycenidz (pls. Lx-Lx101, figs. 18, 
22, 34, 35, 12, 38, 14, 13, 37; 36, 39, 40, 32 and 33). 
