MORPHOLOGY OF THE LEPIDOPTEROUS PUPA, 203 



and the apex of tlie narrow triangular area which is thus formed represents the opening of the 

 oviducts, invisible in this and most individuals of the species, although sometimes seen. 

 Immediately in front of the apex of the above-mentioned area is the second or anterior 

 generative aperture, that of the bursa copulatrix. This is very distinctly marked and is bounded 

 laterally by prominent convex lips ; it thus resembles the form of the male generative opening, 

 but can be readily distinguished in that it is placed in the 8th abdominal segment, while the 

 male aperture is situated in the 9th. 



Fig. 2. X 7. The same pupa as seen from the right side. The posterior part of the seventh abdominal 

 segment is shown in addition to those represented in fig. 1. The number viii. is placed close 

 to the dorsal projection which corresponds to the caudal horn of the larva, and which is very 

 exceptionally developed in this individual. Immediately below the terminal spine (Sp.) is seen 

 a curved line dividing the tenth segment into an upper and a lower (or anal) part. 



Fig. 3. Natural size. The terminal part of a female pupa, as seen from the ventral aspect in a good 

 light. The narrow pointed prolongation of the boundary between the ninth and tenth abdo- 

 minal segments is distinctly seen, although neither of the generative openings were visible in 

 this individual without magnification. The anus is distinct, and the cushions on each side of it 

 (representing the anal claspers of the larva) are somewhat more promiuent than usual. 



Fig. 4. Natural size. The same pupa as seen from the left side. Beneath the reference letter \tii. a 

 normal trace of the larval caudal horn is seen, indicating the exceptional character of fig. 2 in 

 this respect. The trace consists of an anterior slight elevation formed by the soft surface of 

 the pupa rising in the hollow interior of the horn, and a posterior slight concavity caused by 

 the hinder margin of the base being depressed into the soft surface when the horn is bent 

 backwards, becoming nearly horizontal, before pupation. 



Fig. 5. Natural size. The terminal part of another female pupa, seen from the ventral aspect; the 

 opening into the bursa copulatrix, with its lateral lips, is peculiarly distinct. 



Fig. 6. Natural size. The terminal part of a male pupa, seen from the ventral aspect. The opening of 

 the male ducts is distinctly seen, placed between the prominent lips upon the ninth abdominal 

 segment. 



Fig. 7. X 2. The ventral part of the ninth abdominal segment of the last pupa, showing the external 

 reproductive organs more distinctly. The small pit in front of the organ is merely an acci- 

 dental irregularity of the surface. 



Figs. 8-11. The Terminal Abdominal Segments of the Pupa of Smerinthus populi. 



Fig. 8. X 5-25. The last three abdominal segments of a female pupa, seen from the ventral aspect. 

 The anus is concealed in this position, owing to the altogether exceptional size of the anal 

 cushions, which, in this individual, even retain the form of the larval claspers. An elongated 

 opening, surrounded by a raised border, is situated in the normal position in front of the apex 

 of the narrow median prolongation from the tenth abdominal segment. The opening is seen 

 to be divided in two ; it is probable that the posterior division represents the mouth of the 

 oviducts ; the anterior division, of course, corresponds to the bursa copulatrix. The remark- 

 able sculpture of the surface is indicated in the figure. 



Fig. 9. X 5-25. The same pupa, as seen from the left side; the scar of the caudal horn is distinct, and 

 the remarkable size and shape of the left anal cushion is better seen than in the previous 

 figure. 



Fig. 10. X 7. The same pupa, as seen from the left side and behind. The object of the figure is to 

 show the relative positions of terminal spine, anus, and anal cushions. These bear precisely 

 the same relation to each other as the anal flap, anus, and anal claspers of the larva, thus 

 SECONB SERIES. — ZOOLOGY, VOL. V. 31 



