' PHILIP A. MUNZ 39 



and although an arrangement can be made which seems to follow 

 the general line of descent in this subfamily, and to indicate what 

 tendencies have been followed out venationally, it has been so far 

 impossible to base any key on venation, since the genera as now 

 recognized have considerable variation within themselves. It has 

 been necessary, therefore, to make use of structural characters for 

 this subfamily, and to make a key for which no claims of natural 

 relationship can be made, but which is merely an attempt to aid in 

 identification. Before this difficult group can be finally worked 

 out, however, much more material must be studied than it has 

 been possible to study for this paper. 



The nomenclature of veins used in the keys is the same as that 

 shown in the wings of Agrion and Argiocnemis in the first part of 

 the paper. The number of the figure appearing in connection 

 with each genus refers to the plates at the end of the paper. For 

 the following genera neither figures nor specimens have been 

 available: Paraphaea., Caliphaea, and Pentaphlebia among the 

 Agrionidae; and Orolestes, Platylestes, Protolestes, Mesopodagrion, 

 Metagrion, Allolestes, Argiagrion, Heteropodagrion, Mesagrion, 

 Mesocnemis, Momhagrion, Myagrion, Nesocnemis, Nesobasis, Neiir- 

 agrion, Onychargia, Paracnemis, Pericnemis, Phasmoneura, Sten- 

 ocnemis, and Thermagrion among the Coenagrionidae. 



The material used for study of the other genera was that in the 

 collections at Cornell University, at the Academy of Natural 

 Sciences at Philadelphia, at the National Museum, in the private 

 collection of Air. C. H. Kennedy, and some borrowed from Mr. 

 E. B. Williamson, the Carnegie Museum, and the Museum of 

 Comparative Zoology.- In addition to this free use was made of 

 those figures and keys which appear in the literature, and of some 

 photographs sent by Mr. H. Campion of the British Museum. 



Key to the Suborders of Odonata 



1 (4). Fore and hind wings essentially similar; in repose, held vertically or half- 

 opened; eyes far apart. A quadrangle present. Males with two superior and 

 two inferior abdominal appendages 2 



2 (3). Area between M4 and Cui just beyond MA as broad as that between Cui 

 and posterior margin of the wing. Quadrangle of hind wing and that of fore 

 wing quite different in shape, the former twice as wide distally as proximally. 

 Sectors of the wing (except M^) zigzag ANISOZYGOPTERA (p. 40) 



MEM. AM. ENT. SOC, 3. 



