l8 . A VENATIONAL STUDY OF THE ZYGOPTERA 



two as being an infallible means of determining Coenagrionidae 

 must give way, as has been stated by previous workers. The re- 

 traction of the nodus is a more fundamental difference than the 

 retention of four or five cross-veins and must place the genus in 

 the higher family. Now as to its subfamily ; it is convenient to 

 limit the Pseudostigmatinae to those genera in which the stigma 

 becomes diffused and which have Mia following M2 rather than 

 Ml. If this is done, Thaumatoneura may be placed near the base 

 of the Pseudostigma line. I can readily see, however, that its gen- 

 eral vein-arrangemeat, its large postnodal area, its broad area 

 behind Cu and its retracted nodus may indicate a condition near 

 enough to that of Megaloprepus (fig. 46) to warrant placing the 

 two in the same subfamily. 



To' return to the general discussion of the Megapodagrioninae, 

 it may be said that Rhipidolestes (fig. 52) in the position of the base 

 of M3 shows a decided affinity to the Lestinae, to separate it from 

 which is perhaps as artificial an arrangement as to divide Thauma- 

 toneura from the Pseudostigmatinae. The extreme petiolation and 

 long narrow quadrangle, however, of Rhipidolestes throw it in this 

 subfamily, which may be said really to begin with Podopteryx 

 (fig- 53)- From there on, the adult venation at least, gives a well 

 connected series which has been carefully discussed by Dr. Cal- 

 vert (191 3). As nearly as they can be made to do so the keys 

 show my interpretation of its evolution. M3 and R« at their points 

 of attachment move outward to beyond the subnodus, the quad- 

 rangle becomes elongate, the wing reaches the extreme of petiola- 

 tion, and the number of supplementary sectors is reduced to none 

 other than M^. 



Tillyard (1914), on the basis of the presence of the oblique vein 

 formed the Synlestinae as a group including such genera as Chloro- 

 lestes (fig. 66) and Synlestes (fig. 63), and placed them with the 

 Lestinae. But, as has been shown, this was a dangerous undertak- 

 ing. According to Schmidt (1915) the genera Chlorolestes (fig. 66) 

 and Synlestes (fig. 63) belong to the Lestinae on the basis of the 

 structure of the male genitalia; his figures, however, fail to show 

 any very close connection. Venationally they are not to be placed 

 in the Lestinae; M3 arises very near to or at the subnodus although 



