PHILIP A. MUXZ 19 



the general wing proportions are those of the Lestinae, in wliich it 

 arises far before the subnodus: petiolation has proceeded to the 

 level of half the length of the quadrangle; in the Lestinae it does 

 not reach the arculus. It is true that Cui arches forward just 

 beyond MA as in Lestes (fig. 44), but that is the case in some other 

 genera as well; for example Chorismagrion (fig. 69) and Trineura- 

 grion (fig. 54) and Dimeragrion (fig. 67) to a certain extent. Rhipid- 

 olestes (fig. 52) in its venation is nearer to Lestes (fig. 44). but 

 Schmidt considers it much nearer Megapodagrion (fig. 57) itself on 

 the basis of the penis. 



I have spoken before of the progressive reduction of the sectors 

 in the Megapodagrioninae until all except Mia are gone; when this 

 state is arrived at, the condition to be found in the Coenagrioninae 

 is present. But there are two genera which agree with the Coen- 

 agrioninae in this respect, but which seem better retained in the 

 Megapodagrioninae. These are Chorismagrion (fig. 69) and P'eri- 

 lestes (fig. 70) ; their extreme petiolation, the remote origin of Rs 

 and M3, the arching forward of Cui beyond MA, and the heavy 

 stigma of Chorismagrion are indicative of affinity to Synlestes (fig. 

 63) and Heteragrion (fig. 68) and through its likeness to Chorismag- 

 rion, Perilestes is to be placed at the apex of the Megapodagrion 

 line. 



Just the fact, then, of the presence or absence of supplementary 

 sectors is not a safe criterion by which to separate the Megapo- 

 dagrioninae from the higher forms. It is indeed an accompani- 

 ment of specialization and reduction and is a convenient character 

 to use. Generally mere presence or absence is not so reliable a 

 matter as might l)e supposed, since two forms without a gi\en char- 

 acter may ha\e arisen independently from two very distinct an- 

 cestors, one with the character ijresent in one wa>', another with it 

 in quite a different way. 



It is probable, however, that the forms placed by de Selys in the 

 legions Agrion and Platycnemis have been derived from others, 

 closely related to Megapodagrion (fig. 57). in which petiolation has 

 not reached the lexel of Ac and in which Mn arises i^efore the sub- 

 nodus. A wing like that of Megapodagrion with the suj^plementary 

 sectors removed would be much like Platycnemis (fig. 74). I\t- 

 haps the distinction between the legion Podagriou on the one hand, 



MEM. AM. EXT. SOC, .V 



