1 6 A VENATION AL STUDY OF THE ZYGOPTERA 



group has been in a different direction from that in the other Coen- 

 agrionidae. The presence of the oblique vein between AI2 and Rg 

 is of course a character recalling the condition to be found in the 

 Anisoptera, but it seems to be a rather dangerous one on which to 

 depend too extensively if it means that Epiophlebia must be placed 

 in the same category as the Lestinae. Pseudolestes (fig. 38) and 

 Ortholestes (fig. 39) have the general venation of the Lestinae and 

 are intermediate between the higher Lestine genera and Diphlehia 

 (fig. 34). Yet they do not possess the oblique vein, at least it is 

 not distinct. Cannot this cropping out of a primitive feature be 

 a secondary matter, a reappearance? It is evidently so in the case 

 of the square quadrangle of Protoneura, Lestoidea, and Disparo- 

 cypha. A single character is dangerous to use too far to the exclu- 

 sion of others, although it may sometimes seem necessary to do so. 

 The oblique vein is present also in Chlorolestes (fig. 66) and Syn- 

 lestes (fig. 63) yet the rest of the venation does not suggest the 

 Lestinae. This oblique vein is of course present in those genera 

 in the nymphs of which the trachea for Rg is joined to the trachea 

 for M2. Whether this attachment of the trachea is to be taken as 

 more or less important than the adult venation is the question. It 

 seems reasonable to lay more stress on the latter since in it several 

 other characters unite in placing Chlorolestes and Synlestes in the 

 Megapodagrioninae. 



Pseudolestes (fig. 38), Ortholestes (fig. 39) and Rhipidolestes (fig. 

 52) show a connection between the Lestinae and Megapodagrion- 

 inae, and these two subfamilies can be considered as offshoots from 

 the same general region of the Agrionidae. Their close affinity 

 warrants the retention of the subfamily name for the Lestinae 

 rather than the use of a family name. Of the forms included here 

 under Lestinae Pseudolestes (fig. 38) is undoubtedly the most primi- 

 tive, in having the quadrangle like that of Diphlehia (fig. 34) and 

 in its large number of supplementary sectors. Ortholestes (fig. 39) 

 comes next and is followed by the Lestine genera proper: Archi- 

 lestes (fig. 40), Megalestes (fig. 41), Orolestes, Platylestes, Lestes (fig. 

 44), Sympycna (fig. 42), etc. The general tendency is that of 

 reduction, combined with straightening of the veins at the tips. 

 Many sectors and veins are somewhat zigzag, and there develops 



