PHILIP A. MUNZ 15 



many separate branchings took place, even amongst this one por- 

 tion of the Suborder? The origin of the tribe Agrionini^ is doubt- 

 ful, for their acute quadrilateral might yet be proved to be the 

 reduced remnant of an originally weak Anisopterid triangle-forma- 

 tion. Finally, standing out clear from all the rest as the most 

 recent ofTshoot from the Anisopterid line, we see the Epiophlebia- 

 Synlestes-Lestes line of descent, which branched off from that line 

 not very far from the beginnings of the Gomphinae, and whose 

 sharply angulated quadrilateral is almost certainly an Anisopterid 



remnant," 



Following out his theory, Mr. Tillyard places this "line of de- 

 scent" in a family Lestidae and divides it into the following sub- 

 families: Epiophlebinae, Lestinae, Synlestinae, and Heterophle- 

 binae, the last named containing fossils only. It is now known 

 that Epiophlebia (fig. i) is far from being near the Lestinae not 

 only venationally, but on the basis of the genitalia, it is of far too 

 generalized a nature to be placed near them, although an oblique 

 vein between M2 and Rs is present" in both subfamilies and many 

 of the sectors are very zigzag. The Zygoptera cannot be con- 

 sidered as derived from the Anisoptera, but form a dichotomy 

 with them, both arising from the ancient Anisozygoptera. The 

 argument that all Zygoptera with the regular quadrangle are 

 primitive is also unfounded; the regularity of the quadrangle, that 

 is, its squareness distally, is not so fundamental a thing as it might 

 seem. Those forms which are perhaps the most highly specialized, 

 those in which Cu2 is reduced to a cross-vein, have the^ square 

 quadrangle; yet this condition arises independently three times, in 

 Disparocypha (fig. 37). in Lestoidea (fig. 45) and in the Protoneur- 

 inae. I cannot, therefore, agree with any of the views expressed 

 in the above quotation as regards the phylogeny of the Zygoptera. 

 This subject can, however, be more fully discussed in treating each 

 subfamily independently. 



The Lestinae 

 The Lestinae, as has been said before, include those Coenagrion- 

 idae in which the vein M3 arises nearer the arculus than the sub- 

 nodus, therefore it comprises the legion Lestes of de Selys. This 

 feature is an ancient and primitive one and specialization in this 



2 Agrionini is Coenagrionidae of this paper. 

 MEM. AM. ENT. SOC, 3. 



