354 CHARLES T. BRUES. 



Die kleine Querader fehlt, well die in der Strecke ac enthalten 

 ist." 



This comparison is very striking and were it not for the funda- 

 mental differences in metamorphosis and in other organs, might 

 be conclusive. It is further strengthened by the fact adduced 

 by Becker that certain of the macrochaetae covering the body are 

 in both families provided with chitinous bristle-like projections. 

 On the other hand, Schiner has with almost equal facility re- 

 duced the Phorid wing to a more generalized type of brachy- 

 cerous venation according to the following scheme (see Fig. 4). 



The main differences between 

 this and the arrangement by 

 Girschner lie in the interpre- 

 tation of the fourth vein in- 

 volving the presence of the 

 cross-vein and the presence 

 of the anal vein. Schiner's 



FIG. 4. Wing of Mora sp., as interpreted designat j on o f t h e indistinct 



by Schiner. 



thickening along the costa 



beyond the tip of the heavy veins as a " Fortsetzung der ersten 

 Langsader " I cannot exactly understand, but it involves no im- 

 portant point. 



Of the two views, that of Girschner accords more closely with 

 the actual wing venation, and will I think be partly accepted with 

 the exception of several points mentioned on a later page, by 

 all who will study carefully a series of wings. That this 

 similarity between the Mycetophilid and Phorid wing involves 

 genetic relationship does not necessarily follow, however. As 

 suggested on a previous page, specialization of wings often fol- 

 lows more or less parallel paths in diverse groups, and this 

 seems to be especially true in those where a loss in com- 

 plexity of structure is brought about by parasitism, secretive 

 habits, or minute size. Turning to the Dipterous family Hippo- 

 boscidae, widely removed from those previously discussed, we can 

 see a strikingly similar condition to the one assumed by Girschner 

 for the Phoridas. Fig. 5 shows the wing of a species of 01- 

 fersia, a genus of Hippoboscidae. The heavy veins are confined 

 to the anterior basal region, while several oblique light veins tra- 



