34 



DIPTERA OF NORTH AMERICA. 



[PART IV. 



vein between its origin and the emission of the third longitudinal 

 vein. The petiole of the first submarginal cell is the portion of 

 the second longitudinal vein between the tip of the prsefurca and 

 the inner end of that cell. In order to describe the relative 

 position of the tips of the veins and of cross- veins, I have used 

 the term opposite ; two points are opposite each other when, pro- 

 jected on the longitudinal axis of the wing, they appear equi- 

 distant from its basis. The following diagram explains the other 

 terms, which have been used by me : — 



Diagram of a wing with two submarginal and Jive posterior cells 

 (Cladura indivisa). 



1. Costal. 



2. Subcostal. 



3. Marginal. 



3*. Inner marginal. 



4. First submarginal. 



Cells. 

 5. Second submarginal. 

 6-10. First to fifth posterior. 



11. Discal. 



12. First basal. 



13. Second basal. 



14. Anal. 



15. Axillary. 



16. Spurious. 



Veins. 



b I. Auxiliary. 



c m. First longitudinal. 



h n o. Second longitudinal. 



Prsefurca. 



Anterior branch of the second 



1. vein. 

 Posterior branch of the second 



1. vein. 

 Petiole of the first submarginal 



cell. 

 i p. Third longitudinal. 



hi. 

 It n. 



ko. 



ik. 



dqrst. Fourth longitudinal. 



q r. Fork of its anterior branch ; the 

 posterior branch of this fork, 

 ending in r, is Mr. Loew's an- 

 terior intercalary vein. 

 S t. Fork of the posterior branch of 

 the fourth vein; the branch 

 of this fork, ending in t, is 

 Mr. Loew's posterior inter- 

 ca lary vein. 



e u. Fifth longitudinal. 



fv. Sixth longitudinal. 



g w. Seventh longitudinal. 



1 In my paper : Description of some new Genera and Species of North 

 American Limnohina, Proc. Phil. Entom. Soc. 1865, p. 225, I have called 

 this cell the second marginal ; the proper term, however, in accordance with 

 the terminology originally adopted hy Macquart, is first submarginal. 



