210 ME. E. B, POULTON ON THE EXTERNAL 



associated with the fact that motion is possible only at these intersegmental junctions. The 

 rudimentary spiracle on the eighth abdominal forms a great contrast with those on the anterior 

 segments. The junction of the terminal spine with the tenth abdominal is marked by a line. 

 An oblique furrow extending posteriorly into the tenth abdominal probably represents an 

 incomplete division into a dorsal and ventral part. 



Figs. 21-23. The Terminal Abdominal Segments of the Pupa of Melanippe fluctuata. 



Fig. 21. x 26. The last four segments of a female pupa seen from the ventral aspect. The boundaries 

 of the median prolongation of the tenth abdominal are indistinctly visible and dis- 

 appear towards the apex. This is a result of the polished surface of the pupa. Towards the 

 posterior boundary of the eighth abdominal, the two generative openings are distinctly visible 

 and are almost fused. It is impossible to feel any certainty as to the segments to which they 

 belong, in this species. The anus (A) is very distinct and situated on a raised oval area. The 

 terminal spine (Sp.) is distinctly segmented off from the tenth abdominal; it bears four bristles, 

 the two central ones being stouter and larger than the others. 



Fig. 22. x 14'5. The last four segments of another pupa (sex unnoted), seen from the dorsal aspect. 

 The separation of the base of the spine from the tenth abdominal is very distinct. The median 

 dorsal part of the anterior margin of the latter segment is extremely irregular. 



Fig. 23. x 26. The last four segments of the female pupa represented in fig. 21, as seen from the right 

 side. The furrow at the base of the terminal spine is very distinct. There is an oblique 

 furrow extending posteriorly from the anterior margin of the tenth abdominal, as in the pupa 

 of Amphidasis betularia (compare fig. 20). 



The remaining Pupae figured on Plate XXI. are those of Rhopalocera. 

 Figs. 24, 25. The Terminal Abdominal Segments of the Pupa of Papilio podalirius. 



Fig. 24. x 7. The last three segments of a female pupa, seen from the ventral aspect. In this and the 

 next pupa the surface-sculpture has been carefully figured. The opening of the bursa copu- 

 latrix is distinct on the eighth abdominal ; there is a distinct median prolongation from the 

 tenth abdominal, and the posterior generative opening is probably represented by the median 

 line along its anterior part. The anus (A) is distinct, and there is a flattened area in front of 

 it which terminates anteriorly in a raised rounded border overhanging the median prolongation 

 of the tenth abdominal, and forming a very characteristic appearance. 



Fig. 25. x 7. The same parts in a male pupa, seen from the same direction. The male organs are 

 distinct and characteristic in form and position. 



Figs. 26, 27. The Terminal Abdominal Segments of the Pupa of Papilio machaon. 



Fig. 26. x 7. The last three segments of a female pupa, seen from the ventral aspect. The generative 

 openings resemble those of Papilio podalirius (fig. 24) . The position of the posterior opening 

 on the median prolongation of the tenth abdominal is more distinct than in the latter pupa. 

 The raised border in front of the anus (A) exhibits a tendency towards division into two 

 parts. The part of the pupa represented in the figure is somewhat asymmetrical. 



Fig. 27. x 9. The median ventral area of the ninth and adjacent parts of the eighth and tenth abdominal 

 segments of a male pupa, seen from the ventral aspect. The male organs are distinct and 

 characteristic. The raised border overhanging the male organs is not divided so deeply as that 

 represented in the last figure. 



