BY VEltA IRWIX SMITH. 



519 



ment from which they originate. In the specimen shown in PI. xxvii., tigs. 3 

 and 4, the appendages had been stretched out for examination, and had not com- 

 pletely resumed their normal closely-packed condition when figured. The seg- 

 ments of the antennae and the limbs are indicated only by faint grooves in the 

 uniform, tinely-granular, white matter of which all the appendages are composed 

 at this stage. 



The halteres are relatively much larger than in the imago, and appear 

 clearly as the rudiments of meta-thoracic wings (PI. xxvii., %. 4). 



The first appearance of colour on the body is in the region of the eye rudi- 

 ments. These soft, white, rounded prominences assume a yellowish tinge about 

 the same time that the thoracic appendages, still white and indistinctly divided 

 into segments, unfold, and extend down over the ventral surface of the body. 

 As the eyes deepen in colour, the yellow tinge extends over that part of the 

 head which is orange-coloured in the adult female. 



Text-fig. 16. Diagram showing way in which larval case of pupa is opened up. (x 11). 

 Text-figs. 17-20. Metamorphoses of posterior end of larva during, pupation, (x 12). 



Fig. 17. Lateral view of early stage. Pig. 18. Ventral view of later stage. 



Figs. 19-20. More advanced puirae, lateral views. 7th sp., spiracle of 7tli 



abdominal segment. 



At this stage the terminal abdominal segment loses its larval character, and 

 becomes slightly bilobed at the tip (Text-fig. 18), while a bilobed protuberance 

 gTOws out from its ventral surface. The latter probably originates from the 

 upper, or eighth abdominal segment, while the bilobed tip belongs to the ninth 

 (fused) segment. 



The development of this terminal, or fused eighth and ninth segment, into 

 the external genitalia of the adult fly, is the most noticeable feature of later pupal 

 growtlr. It has been followed out in more detail in the female than in the male, 

 and is shown in Text-figs. 17 to 20. The male pupae secured did not show the 

 same range of developmental stages, but eight distinct abdominal segments are 

 present in all. 



Other changes take the form of depositions of colouring matter, and of 

 chitin in various parts of the body, as the segments of the appendages become 

 more clearly defined ; and the outgrowth of hairs on these segments, and of a 

 fine pubescence on the abdomen (PI. xxvii., fig. 6). The wing sheaths lie flat 

 against the ventral surface of the body, and cover the first and second abdominal 



