OF THE MILK-WEED BUTTERFLY. 15 



EXPLANATION OF THE PLATES. 



Plate 1. 



Fig. 1. Lateral view of Danais Archippus, female, X6. 



Head, a., Antenna ; o., Occijiut ; cl., Cly]ieus ; nix., Proboscis ; />., Labial palp. 



Thokax. I, Pro-, II, meso-, III, meta-thoracic somites, s., scutum ; sm., scutellum ; psni., post scutel- 

 lum ; epm., epimerum ; eps., episternum ; ca;., coxa ; tr., trochanter ; f., femur ; these parts are marked \ \ or ^, 

 as they belong to the pro-, meso-, or metathorax, respectively. Sp}, first spiracle ; w} and w.% fore and hind 

 wings. 



Abdomen. 1 to 9, the nine somites of the abdomen ; sp?, sp?, second and seventh abdominal spiracles 

 i.e., the spiracles of the third and eighth pair. X6. 



In this figure the membranous portions of the integument are dotted. 



Fig. 2. Lateral interior view ( X6), showing the internal organs in their natural relations, after the removal 

 of the right half of the integument, together with the tracheae, and fat-body, i to in, somites of the 

 thorax ; 1 to 9, of the abdomen. 



Alijientakt Canal and Appendages. ^^A., pharjTix ; s.d., and s.gl., salivary duct and gland of the 

 right side; oc, oesophagus ; /!r., food reservoir; St., stomach; i., small intestine; c, colon ; ?•., rectum ; a., 

 anus ; in.v., malpighian vessels. 



Haemal System, h., heart or dorsal vessel ; ao., aorta ; a.c, aortal chamber. 



Nervous System. (Dotted in the figure), br., brain; g}, sub-oesophageal ganglion; t.g., compound 

 thoracic gangla ; a.g.^, a.g.*, first and fourth abdominal ganglia. 



Female Reproductive Organs, c./)., copulatory pouch ; v., vagina; o., oviduct, and o.o., its external 

 opening ; r.ov., base of the right ovarian tubes turned down to expose the underlying organs ; l.ov., left ovarian 

 tubes in position, and ov.c, their termination ia four cords ; sp., spermatheca ; a.gl.^, part of the single acces- 

 sory gland ; a-gl!^, one of the paired accessory glands ; only the base of its mate is shown. Other letters as 

 in fig. 1. 



Fig. 3. Front view of head, XlO. oc, compound eyes; a, antennae; cl., clypeus ; lb., labrum ; md., man- 

 dibles ; mx., base of proboscis ; mx.^)., tubercle representing maxillary palp ; s.g., cheek ; or., orbit. 



Fig. 4. Interior view of the bottom of the head, the top having been cut away, showing in the middle the 

 pharyngeal sac with its five muscles — the frontal,ym., the dorsal pair, dm., and the lateral pair, Im.; cl., cly- 

 peus; cor., cornea of the compound eye (the left eye is not drawn) ; oe., oesophagus; pni., one of the large 

 muscles which move the labial palp. 



Fig. 5. Horizontal section of head through the pharyngeal sac. ^:>A., pharynx ; hj^h., hy]3opharynx, show- 

 ing the papillae dotted over it; f.m., frontal muscle; ni., labial paljj muscles; s.d., salivary duct. 



Fig. 6. A section through a bit of wing and a scale ; and fig. 6a, the same, the section passing through a 

 scale pedicel; cu., cu.\ the upper and lower cuticular membranes of the wing. With ^ inch objective. 



Plate 2. 



Fig. 7. Longitudinal section through the head giving a view of the interior of the left half ; mx., the left 

 maxilla whose canal leads into the pharynx ; hph., floor of the latter showing some of the papillae of taste ; 

 oe., oesophagus; cL, clypeus; ep.v., epipharyngeal valve; s.d., salivary duct; d.m. and f.m., one of the dorsal 

 and the frontal muscles which hold the pharyngeal sac in its position. 



Fig. 8. Tip of the proboscis sliowiug the arrangement of the cuticular rings and blocks, with the 

 interspersed papillae. With I inch objective. 



Fig. 9. Longitudinal section of proboscis ; the canal, c, is shown above ; lower down the trachea, (r., and 

 the nerve, n. ; while the diagonal muscles, m., overlie them. These are spaced somewhat wider than in na- 

 ture, for the sake of clearness. The right edge is the outer one. J inch objective. 



Fig. 10. Transverse section of proboscis, showing the two maxillae united by the dove-tail joint, and 

 forming the interior canal, c. ; the air tubes, tr. ; n., nerve ; m. and m.% the two sets of muscles, more or less 

 displaced in the cutting. J inch objective. 



