16 ANATOMY OF THE MILK-WEED BUTTERFLY. 



Fig. 11a, b, c and d. Sections through the integument of the proboscis, showing the different shapes of 

 the cuticular elements and the lamination of the cuticle, cu.; hy., hypoderm or matrix. Fig. lie shows two 

 of the cuticular elements separating from each other. -^ inch objective. 



Fig. lie. Cuticle of posterior region of the proboscis from outside; each cuticular block being here pro- 

 longed into a spine. ^ inch objective. 



Pig. 12. Cuticular processes clothing the upper central portion of the food-reservoir. The longitudinal 

 and transverse muscular fibres are seen beneath. ^ objective. 



Fig. 13. Lateral view of the tip of the abdomen in the male ; 7, 8, 9, seventh, eighth and ninth somites 

 of the abdomen ; p., penis ; f.c, false clasper, overlying the real olasper, c, which is shown uncovered in 

 fig. 13a, by the removal of the whole 8th somite ; h.s., hair sheath torn open above, showing the protrud- 

 ing bundle of hairs ; m., muscle. X 8. 



Fig. 14. Lateral internal view of the male abdomen, showing the genitalia in situ ; t., testis ; v.d., the 

 double vas deferens ; d.e., ductus ejaculatorius; p.b., interior view of the penis bulb; ^.s., penis sheath; r.p., 

 retractor penis ; pr., internal process of the ninth somite affording the attachment of the retractor penis; 

 the posterior wall of the process is cut away; c, clasper ; f.c, false olasper ; other letters as in fig. 2. X 8. 



Fig. 15. Interior of the exoskeleton of the seventh, eighth and part of ninth abdominal somite,, male. 

 The figure 9 is placed on the ventral arch of the ninth somite, which sends forward the process, pr., for the 

 attachment of the retractor penis as shown also in the j^receding figure. The dotted sui-face represents the 

 membrane, connecting the eighth and ninth somites. This membrane is pierced above by the hair-bundle ; 

 h.s., hair-bundle sheath ; r.m., its retracting muscle. X 8. 



Fig. 16. Horizontal section through the tip of the male abdomen showing the penis, p., and its extensor 

 and retractor, e.p., and r.p. ; p.b., penis bulb ; p.s., sheath ; d.e., ductus ejaculatorius ; h.b., cut through hair- 

 bundle ; s.tn., intersegmental muscles. X 8. 



Fig. 17. Male organs, natural size; t, testis, with its supporting tracheae, tr.; «.(?., vas deferens; gl., 

 gland ; d.e., ductus ejaculatorius. 



Fig. 18. Portion of testis showing the Histribution of the tracheae of the left fifth abdominal spiracle. 

 The branching of only one of the main tracheal stems is figured. 



