THEREVID^. 



541 



Type of venatio7i of the Therevid^, 



Fio. Zll.—Tliereva annulata i. 



Longitudinal (or long) veins. 



a Costa (o7' costal vein), 

 h Mediastinal {or auxiliary) vein, 

 c Subcostal {or \st longitudiiml) vein. 

 d Radial {or 2)id longitudinal) vein. 



e Cubital {or 3rd longitudinal) vein ; always with a simple fork which includes the 

 tip of the wing. 



e; Upper branchj ^ j ^^^^-^^^ f^^.j, 

 e- Lower branchj 

 / Discal {or Ath langitudinal) vein ; always including all the discal cell and all the 

 veuis issuing from it. 

 f ' Upper veinlet "l 



f'^ (Second veinlet r from the discal cell. 

 f^ Third veinlet J 

 g Postical {or 5th longitiidiiud) vein ; always with a simple fork, but the branches 

 of the fork usually uniting with veins on either side before reaching the 

 wingmargin. 



gi Upper branch! ^ j • ^ ^ .j^ 



g- J^ower branch j ^ 



h Anal {or Qth longitudinal) vein. 

 i Axillary vein. 

 k Pra3furca = the common stem of the radial and cubital veins. 



Ambient vein = the continuation of the costal vein round the hindmargin of the 

 wing. 



Cross {or transverse) veins. 

 w Humeral cross-vein. 

 X Discal {or middle) cross-vein. 

 y Lower {or small) ci'oss-vein. 



Anal cross-vein =g- = the lower branch of the postical fork. 



Cells. 



1 Costal (o?" mediastitial) cell. 



2 Subcostal cell. 



3 Marginal cell. 



4 Submarginal cell. 



4^ Second submarginal {or cubital) cell {or cubital fork-cell). 



5 First posterior {or suha'pical) cell. 



