AFFINITIES OF THE DIPTEROUS FAMILY PHORID.K. 357 



vein represents the fourth and that what has been called the fourth 

 is an adventitious vein. The process of coalescence in the Hip- 

 poboscidas has suggested this. 1 Here (see Fig. 6) the first light 

 vein arises at the cross-vein which is near the middle of the third 

 vein. This vein is undoubtedly the fourth on account of its 

 association with the posterior end of the cross-vein yet it occu- 

 pies exactly the same place as the second light vein in the Phoridae. 

 This is a far more probable sort of coalescence by shortening of 

 the cross-vein than an approximation of veins throughout their 

 entire length which would be necessary to bring the fourth vein 

 near the tip of the the third where the adventitious vein originates. 

 Other points in favor of an adventitious origin are the appearance 

 in some cases of a nebulous thickening in the same space in 

 the Hippoboscid wing and the great variability of this vein in 

 the Phoridee. It also removes the difficulty which Coquillett 

 saw in recognizing three posterior veins in the Phoridne which he 

 thought would exclude them from membership in the Cyclor- 

 rapha. I think also that the slight thickening near the costa 

 beyond the tip of the third vein is also an adventitious vein if it 

 can properly be designated as a vein. 2 



I agree with Girschner and Becker that the sixth (anal) vein is 

 lost, or obsolete, and that the last vein (fourth light vein) repre- 

 sents the seventh or axillary. There can be no doubt that the 

 short anterior branch at the tip of the third vein represents the 

 second which is fused with it to this point. In the more special- 

 ized genera (e. g., Hypocera, Puliciphora) the fusion is complete 

 to the tip. 



PUBLIC MUSEUM MILWAUKEE, Wis., 

 January 9, 1907. 



1 There are many other developments among the Phoridas which parallel those of 

 the pupiparous Diptera such as the Hippoboscidae. Briefly summarized they are ( I ) 

 The degeneration and sometimes ultimate disappearance of the wings. (2) The 

 production in the apterous or subapterous forms of very large eggs which distend the 

 abdomen greatly and are even thought in some cases (cf. \Yasmann, '02) to develop 

 to the larval or pupal stage before being laid. (3) The similarity in wing venation 

 already mentioned. (4) The degeneration of the eyes (cf. Streblidce, Brues, 04% 

 Fig. i). 



These resemblances are undoubtedly the result of parallel development, but as 

 Professor Williston has suggested to me in a recent letter, they tend to weaken the 

 value of the group Pupipara. 



2 Schiner refers to it as a part of the first vein. 



