XXIX 
specimen of Merope are connected by a transverse nervule ; but the addi- 
tional nervule (instead of being incomplete and confined to the right hind 
wing) is found in both hind wings and thoroughly unites the subcostal 
nervules. In this manner a perfect addi- 
tional cell is formed (see a in figure) imme- 
diately adjoining and above the ordinary 
A.- ^■.■^■■yir\^.^ J Ij discoidal cell, and extending beyond it. The 
subcostal nervules are 'angulated and drawn 
together ' by the transverse nervule, quite as 
Mr. Murray describes in P. Clodius, and the 
additional cell is of the same size and shape in both hind wings. It is 
observable that the true discoidal cell is not at all distorted, but of the normal 
size and form in both hind wings. This interesting example of P. Merope 
was taken by Mr. J. H. Bowker on the Boolo Piiver, a small tributary of 
the Tsomo, in Kaffraria Proper. 
"I have in another place (Trans. Linn. Soc, vol. xxvi. p. 501, note) 
commented on the remarkable neuration of the Papiliouidae, and pointed 
out how the presence of more than one cell enclosed by anastomosing 
nervures constitutes an indication of affinity to the Heterocerous groups of 
Lepidoptera ; and this indication acquires additional significance in view of 
the interesting facts recorded by Mr. Murray respecting butterflies of this 
family, and of the circumstance of the tendency to form additional wing-cells 
finding such mai'ked development in the specimen of P. Merope above 
described. There can, I think, be little doubt that (as Mr. Murray suggests 
in reference to the pre-discoidal cell discovered in some examples of Thais 
Polyxena, W. V.) these exceptional cases of neuration are referable to rever- 
sion to ancestral characters, and point to a remote community of origin 
between the Papilionidse and the higher Heterocera. 
" In my discussion [loc. cit., pp. 501-2) of this question of the position 
of the PapilionidiB, I overlooked Boisduval's account (Faune Ent. de 
Madag., &c., pp. 6 and 113) of the larva of the splendid Urania Rhipheus, 
or I should not have quoted Cerura as affording the only other instance 
among the Lepidoptera of organs analogous to the Y-shaped tentacle of the 
Papilionide caterpillars. Boisduval states particularly (on the authority of 
Captain Sganzin, who reared a large number of the Urania) that the larva 
of Rhipheus possesses, * comme dans les Papilio,' ' deux comes retractiles, 
roses, 2)lacees sur h j^remier anneaii,' adding that it exserts them at will 
('fait sortir a volonte'). Mr. Wallace, not only in his paper on Malayan 
Papilionidoe (Trans. Linn. Soc, vol. xxv.), but more recently in his valuable 
' Contributions to the Theory of Natural Selection,' Qnd edit. 1871, has laid 
such stress on the possession of the exsertible Y-shaped organ being, as the 
exclusive character of Papilionide larvae, a sign of the highest development 
of the Lepidopterous Order, that the presence of an apparently identical 
