520 



STLUIES IN LIFK-HISTOKIE.S OF AILSTHALIAN DIPTERA ISRACHYCERA, 1., 



segments. Within tlieni the much crumpled and folded wings can be seen, very 

 dark in colour. The lirst pair of legs extentls down to the tip of the wing, the 

 second pair to the middle of the third segment, and the third pair almost to the 

 fifth segment. The limb sheaths lit loosely over them, and are slightly constrict- 

 ed at the level of each joint. 



The form of the sheaths for the mouth parts is shown in PI. ssvii., fig. 7. 

 They consist of four thin- walled vesicles, two central, upper and lower, with 

 enlarged bilobed extremities, and a narrower one on each side, bluntly rounded 

 at its extremity, and with a small secondary lobe attached to its' upper surface. 

 Through their walls it is jtossible to see portions of the developing mouth parts, 

 at first pale yellow in colour, later darkening to a deep brown. There is a 

 certain amount of rigidity in the pupal skin, so that the vesicles retain their 

 shape unsupported by the underlying organs, these being much smaller than their 

 covering. When the latter is removed it is found that the lateral vesicles enclose 

 the maxillary palps, and the lower median vesicle the "proboscis," its bilobed 

 extremity forming the sheath for the labellae. The parts enclosed by the upper 

 vesicle are very small and inconspicuous, but a careful examination of them 



Text-fig. 21. Mouth parts of pupa tlissected out from pupal slieath, surface view, (x 57). 



Text-fig. 21(;. Labrum epipliaryux of same. 



Text-tig. 22. Back view of the same. 



Text-fig. 23. Portion of sheath of mouth parts, showing; enclosed labrum-epipharynx, and 



palp. 

 fr.cl., f ronto-clypeus ; l.cp., labrum-epipliaryux ; ///>., hypopharyux ; in. p., maxillary 

 palp; pli , pharynx; lab, labella. 



when dissected out (as shown in Text-figs, lil, 22) reveals the presence oT most 

 of the structures described by Peterson (1916), and shown in his figures of 

 Stratiomyia apicula. Within the proximal end of the vesicle is a small saddle- 

 shaped piece of ehitin, the fronto-cly))eus, which supjiorts. on its lower, invei-ted 

 V-shaped nuirgiu, a triangidar, beak-like process, projecting outward from tlu! 

 face, the labrum-epipharynx (Text-fig. 21h). In the i)upa, the line ol' juiu-tion 

 between the constituent parts is still visible, and the underlying epipharynx is 

 clearly distinguishable from tlie lal)rum. I>ying below this structure, and still 

 quite separate from it. is the lliin grcKivcd hypopharyux. In the inuigo (PI. 



