Dec., '08] ENTOMOLOGICAL NEWS. 457 



ment of the cells below Cu, where two or three large penta- 

 gonal areas were marked out by stronger veins. On the whole, 

 however, there did not seem to be any reason why the fossil 

 should not go in Basiacschna, and it could certainly not go in 

 any of the other genera, unless it were Acschna of the type of 

 Ae. jnncca. 



At this point the other half of the wing was found, and it 

 was seen at once that the radial sector was branched, throwing 

 it decisively out of Basiacschna, and into Aeschna or some 

 very closely related genus. Further investigation showed that 

 it was in fact the hind wing of Aeschna solida Scudder, based 

 on a single anterior wing. Another front wing of Ae. solida 

 was found by Mr. S. A. Rohwer in 1907 (Station 14, Floris- 

 sant). I would not have recited the above merely to record 

 the birth and early death of a mistaken idea; it is given be- 

 cause it seems to be really significant in relation to the evolu- 

 tion of these insects. Dr. Needham (Proc. U. S. Natl. Mu- 

 seum, xxvi. p. 735) writes that in Aeschna and its nearest 

 allies : 



"There is this added feature the radial sector has become 

 forked. It will be observed that the anterior branch of this 

 fork is separated from vein M , by a single row of cells, and 

 that in the same place in Basiaeschna there is a line of cross- 

 veins tending to straighten out. The anterior branch of the 

 fork is developed out of this line of cross-veins. In the Austral- 

 ian Acschna brcvistyla all stages of its completeness and in- 

 completeness may be found in a series of specimens." 



The study of other features of the wing shows that Basiac- 

 schna has indeed much in common with Acschna, so that they 

 should doubtless stand together as the connecting links of the 

 series with branched and unbranched radial sectors. 



In Acschna itself, however, we have two types of branching 

 of the radial sector. In Ae. juncea, Ae. constricta and the fos- 

 sil Ae. solida, the upper branch comes off from the lower quite 

 abruptly- and has all the appearance of being but a branch. In 

 Ac. californica and in Coryphaeschna the effect is reversed, 

 and the upper branch actually appears to be the continuation 



