I03 



The method of specialization of wing-veins which has 

 taken place in the Hymenoptera can be most easily seen by 

 a study of the fore wings of certain saw flies. The most use- 

 ful for this purpose that we have found belong to the genera 

 Pamphiliiis and Macroxyela. If we are right in our interpre- 

 tation of the wings of these insects, there is preserved in 

 each genus all of the primitive wing-veins with a single ex- 

 ception. And, as in each of these genera a different vein is 

 lost, we are able to make a figure of a typical wing from a 



Fig. 7. — The cells of a typical hymenopterous wing." 



Study of the two genera. Figures 6 and 7 represent such a 

 wing ; in the former the veins are lettered ; in the latter, the 

 cells.f 



In the wings of these sawfiies the anal furrow and the 

 median furrow are both well marked, and are in the typical 

 positions ; that is, the anal furrow is immediately in front of 

 the first anal vein, and the median furrow is in front of the 



^'The cell lettered 5 is probably Sc^. When it is thickened and opaque, as 

 is frequently the case in this order, it is termed the stigma. 



t Figures 6 and 7 represent the venation of the fore y/'mgol Pamphilius, except 

 that vein R.^, which is lacking in this genus, is added. This vein is well pre- 

 served in Macroxyela, but in Macroxvela vein Cii.^ is lost. See Comstock. 

 Manual for the Study of fir sects, p. 606, fur figures of the wings of these two 

 genera. 



