36 



THE NORTH AMERICAN SPECIES OF DROSOPHILA. 



any at all, and Aulacigaster leucopeza (fig. 18), in which three are 

 present. As the figure shows, these are of a somewhat unusual type; 

 and two of them are attached to a single duct. This is normal for 

 the species, as it has been observed in specimens from Alabama and 

 also from Illinois. 



21 



Figs. 18-31. — Spermathecie. Magnified 250 diameters. 18. Aulacigaster leucopeza. 

 19. Leucophenga varia. 20. Chymomyza amoena. 21. Mycodrosophila 

 dimidiata. 22. Scaptomyza graminum. 23. Drosophila affinis. 24. Dro- 

 sophila busckii. 25. Drosophila caribbea. 26. Drosophila duncani, 

 27. Drosophila funebris. 28. Drosophila guttifera. 29. Drosophila immi- 

 grans. 30. Drosophila melaniea. 31. Drosophila melanogaster. 



According to Wesche (1906), most of the non-muscid Diptera have 

 three chitinized receptacles with three separate ducts, although none 

 is seen in the Dolichopodidse, Lonchopteridse, and Phoridse, and only 



