NOV., '08] ENTOMOLOGICAL NEWS. 407 



vary particularly among the more generalized types of wing 

 venation ; second, the danger of drawing wrong conclusions in 

 regard to the systematic position of a specimen of a species 

 when represented by only one or two individuals. These varia- 

 tions are doubtless of no value in the history of the species, as 

 they probably disappear in the next generation, although I 

 know of no experiments to test this. 



The figures are redrawn from photographs. The markings 

 on the wings, if any, are not indicated in the drawings. 



Explanation of Plate XVII. 



I. Tipula simplex Doane, 2nd posterior cell wanting in both wings. 



2 and 3. Tipula simplex — to show difference in size and shape within 



the species. 

 4 and 5. Pachyrhina ferruginea Fabr, right and left wing from same 



specimen. Note presence of petiole of 2nd posterior cell in 



4 and absence in 5. 



6. Pachyrhina ferruginea Fabr. Note 2nd post, cell broadly sessile. 



7, 8, 9. Tipula aequalis Doane, to show variation in shape of discal 



cell and length of petiole of 2nd post. cell. 

 10. Dicranomyia badia O. S. Note abbreviated vein at end of discal 

 cell and abbreviated branch of the 4th vein; posterior cross 

 vein in normal position. 



II. Dicranomyia badia O. S. Note posterior cross vein before the 



discal cell; also spur on praefurca. 

 12 and 13. Limnobia triocellata O. S. Note difference in the position 

 of the posterior cross-vein in the right and left wing of the 

 same specimen. 



14. Limnobia triocellata O. S. Note supernumerary cross veins in 



submarginal cell. 



15. Dicranomyia stigmata Doane. Note short piece of vein in spurious 



cell. 



16. Limnobia sciophila O. S. Note two interpolated cells. 



17. Tipula simplex Doane. Note interpolated cell. 



