662 BREATHING-APPARATUS OF LARV^ OF MUSCOID FLIRS, 



posterior spiracles are projected into a long tail in order to enable 

 it to breathe while completely submerged. 



The larvte of Stratiomya chamc^ho, another European fly 

 which swarms in water, have a similar, elongated, tail-like pro- 

 jection of the spiracles. The larva? of a Tachinid fly {Gymnosoma 

 rotwiidatum) live in and feed on tiie body of a Shield-Bug, and, in 

 order to breathe, have an elongated, hook-like projection of the 

 spiracles, which is pushed through one of the spiracles in the 

 side of the body of the bug. 



Anasteij>okhina auguk. (Plate Ixx., figs. 4, 4a). 



Anterior S'plracles. — Cap differentiated into two parts. Tu- 

 bules very strong. 



Posterior Spiracles. — The band strong, complete, nut markedly 

 thick, showing no differentiation into two parts as in P. rujifacies 

 and P varipes. The band is thickened round the space which 

 projects the contour outwards at this point. The band is drawn 

 in slightly between the slits, giving the contour a slightly scal- 

 loped appearance. The inner margin of the band projects very 

 sli'ditlv between the outer and middle slits, and less marked! v 

 between the middle and inner slits. The slits are fairly close 

 together at the base, but are well separated otherwise, and do 

 not run quite the full length of the plate. The outer and inner 

 slits are fairly straight throughout their whole lengths. The 

 middle slit is straight for about two- thirds of its length, and 

 then inclines inwards. "Intermediate structure'" always present 

 between the middle and inner slits. " Blister-structure ' well 

 marked on all three slits. 



PoLLKNiA STYGIA. (Plate Ixx., figs.6, 6«). 



^?i<erior tSpirac'/es. — Cap differentiated into two parts. Tu- 

 bules broad compared with tlieir length, and strong. 



Posterior Spiracles. — Band strong and complete. Space at 

 base completely enclosed in the band, which is not projected 

 outward to such an extent as in A. augur. The band is only 

 slightly drawn inwards between the slits. The inner margin of 

 the band projects strongly downwards between the middle and 



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