Séance du 21 Avril 1920 25 



l)r()\vii aller llic lapse of a day or Iwe. Il Moals on llie 

 surr.iee of the waler wilh Ihe body inclined al an angle 

 of about \'r with Ihe suiiaee, and the lespiratory 

 ai)|)endages breakini; the surlace him. xAI'lei- the lapse 

 ol" seven to ten days the lly emerges from the pupal 

 skin ^t allei- about an hour's time its wings (by and 

 it is al)le to lly away. The Hies are able to copulate the 

 same day ; a[)paienlly they do not leed at all, since 

 I have never seen them taKe in food, nor have any 

 traces of food been observed in their alimentary canals. 



The egg. 



The egg of T. mcridionalis is lenticular in shape 

 and vere minute; its dimensions being 0-4 to U.") mm. 

 in length by 0-1 to 2 mm. in breadth. It is opaque 

 and full of yolk granules and the surface of the egg 

 lias a dirty white appearance. They arc irregularly 

 arranged in the mass and unconnected with one 

 another. The egg mass is indelinitc in shape and its 

 total length varies from 2-7 mm. Hatching lakes place 

 6 to 10 days after laying. 



First stage larva. 



After hatching the larva is 3 to 4 mm. in 

 length l)y 0(5 to OS mm. in breadth, cylindrical in 

 shape & does not bear any locomotor ai)pendages, but 

 moves in a vermiform manner. It exihibits practically 

 all the characters of the full-grown larva, with the 

 exception that it is lighter in colour & more transpa- 

 rent ; in addition the radiating filaments of the anal 

 processes do not form quite such a regular circle owing 



