ANATOMY OF THE GOUT-FLY OF BARLEY. 



813 



traclieation of the segment in whose posterior region arises the 

 dorsal commissure from which they take origin. Very little of 

 the dorsal tracheation is supplied by branches from the lateral 

 trunks. 



Text-fiyure 17. 



]ff. niffriventris. Aiitcvior spiracle. The dotted line indicates the 

 surface of the hodv- 



Text-figure 18. 



Posterior spiracle of 3L ntgriventris. 



Puparium. 



Length 5-7 mm. Maximum breadth 1'2 mm. Pi-actically 

 colourless, but appears green owing to colour of pupa within. 

 "Wrinkling as in Chlorops ; wrinkles have a light golden-brown 

 colour. Splitting of pupaiium as in Chlorops except that the 

 vertical splits always meet dorsally and ventrally, so that the 

 thoracic segments always separate off completely in dorsal and 

 ventral halves (except that they may remain attached to the 

 iiymphal integument). 



