MOEPHOLOGY OF THE LEPIDOPTEROUS PUPA. 



201 



rior boundary of the segment, but is especially dilated at its posterior end (see Plate 

 XX. figs. 15, 27, & 29). In a single individual of Orgyia antiaua (Plate XXI. fig. 10) it 

 appears to be placed on a forward extension of the ninth abdominal into the eighth, 

 but in another individual of the same species its position is normal (Plate XXI. fig. 9). 

 We may safely conclude that the anterior generative opening is associated with the 

 eighth abdominal segment. 



The segmental relation of the posterior generative opening is far more difficult to 

 determine. The two views as to its relationship appear to be about equally supported 

 by the figures on Plates XX. and XXI. These are illustrated by woodcuts 10 and 11. 

 In the former the posterior aperture is placed on the ninth abdominal, immediately in 

 front of, but distinct from, the apex of the median prolongation of the tenth abdominal. 



In w r oodcut 11 the aperture is placed on the apex of the prolongation itself, and there- 

 fore belongs to the tenth abdominal segment. In the majority of pupse the opening 

 occurs at the apex, and may or may not be considered to belong to it. This is the case, 

 for example, with figs. 25 and 29 on Plate XX. Whether connected with the apex or not, 



Tig. 12 



Pig .!!• 



the aperture is always placed close to it. The posterior generative opening is often 

 obscure and unrecognizable on the surface (e. g. Plate XX. fig. 1), and is often fused with 

 the anterior aperture (e. g. Plate XX. fig. 8). Even when the two openings are fused and 

 are prolonged into a common invagination, the double nature of the latter is shown by a 

 furrow (Plate XXI. fig. 19). The posterior opening may be surrounded by prominent lips 

 or by a swollen margin (e. g. Plate XX. fig. 15 ; Plate XXI. fig. 15), or it may be without 

 these features (Plate XXI. fig. 3). 



Although the female organs are not asymmetrical like those of the male, they are 

 subject to even greater individual differences. 



The pupae of Rhopalocera possess essentially similar openings, but they are much more 

 difficult to interpret because of the specialization in shape and the amount of surface 

 sculpture. The ventral area of the ninth abdominal may even be entirely hidden (<?. g. 

 the male Nemeobius lucina, Plate XXI. figs. 32 & 33). Pigs. 21-31 on Plate XXI., 



