Vol. xxix] ENTOMOLOGICAL NF.WS. 2O3 



to the above interpretation occur in the commonest Eastern 

 Tricyphona (inconstans O. S.), where veins R2 + 3 are fused 

 basally with R^ for a short distance (see PI. XII, diagram 6) 

 and the r-m cross-vein connects directly with the sector just 

 before its fork, or just beyond the fork on vein 7?5 : some 

 Dicranotae (see diagrams 7 and 10) are quite as in the above. 

 It seems to me that this is due to the fusion of veins Rz + 3 

 with R^. Thus in Rhaphidolabis we get forms (modest a, fig. 

 8, rnbcsccns, cayuya, etc.) where the cell 7? 3 is sessile ; in 

 R. major (fig. 9) it is very short-petiolate, an intermediate 

 condition to that found in R. tcnuipcs (fig. 7). Even in the 

 last named species alone there is considerable variation in the 

 length of this fusion in a series of specimens. This length of 

 the petiole of cell 7?3, i. e., vein Rz + 3+4 (according to the 

 present interpretation) is one of the most variable features of 

 venation in the Dicranotae. 



This interpretation of the venation would give the Pediciini 

 a much more generalized venation than the earlier interpreta- 

 tion, and other features of the adult and larval organization 

 certainly confirm this belief. All four branches of the radial 

 sector are present, the first, R2, being fused with 7?i for a 

 varying distance back from the wing-margin. It will be seen 

 that the Tanydcridac (diagram i), the only crane-flies known 

 where the full complement of branches of the sector is pres- 

 ent and attain the wing-margin unfused, lack the radial 

 cross-vein and this certainly seems to me to be suggestive. 

 If its anterior branch, 7?2, is swung slightly cephalad to fuse 

 with Ri, then we have the apparent radial cross-vein formed. 

 We must await more evidence before we can finally and accu- 

 rately interpret the radial field of the wing in all crane-flies 

 since it is by all means the most plastic field of the wing. 



In Dicranota (diagram 10) and Polyangaeus alone of this 

 tribe the true radial cross-vein is present and here is located 

 far before the tip of Ri, proximad of the upward deflection 

 of R2. 



The diagrams herein shown (Plate XT!) illustrate the fol- 

 lowing points : 



