PHILIP A. MUNZ 25 



of the legion to include this form and the genus Chlorocnemis (fig. 

 130) which is likewise characterized by having Cu2 one cell in 

 length. It is of course evident that these two genera are interme- 

 diate between the old legions Agrion and Platycnemis proper. Yet 

 they are closer to the latter and may easily be considered as coming 

 in the same subfamily with it. 



Chlorocnemis (fig. 130) with its general wing proportions and 

 arrangement of veins is a genus connecting Platycnemis (fig. 74) 

 with such genera as Palaemnema (fig. 136) and Platysticta, which 

 also have a long postnodal area with the longitudinal veins very 

 regularly and evenly placed. Proneura (fig. 131), on the other 

 hand, shows its affinities with the Coenagrion group on the one side 

 and Neonenra (fig. 133) and related genera on the other, in it are 

 found the pentagonal cells near AI4, the bend of M 1+2+3 before the 

 subnodus, and the small number of the cells of the wing and a short 

 vein Mia. 



After Cu2 has become reduced, the next step in the evolution of 

 the Protoneiirinae seems to have been the atrophy of that part of 

 the anal vein beyond Ac. Thus in Disparoneura (fig. 132), Peri- 

 sticta (fig. 134), Neonenra (fig. 133), and Idioneura (fig. 135) it 

 extends to the medio-anal link; in Palaemnema (fig. 136) and the 

 old genus Platysticta (fig. 137) it ends before MA on the posterior 

 edge of the quadrangle, and in Hypostrophoneura on the hind mar- 

 gin of the wing. In the higher forms it does not extend beyond Ac, 

 which then is generally moved nearer the base of the wing until in 

 Nososticta (fig. 151), Isosticta (fig. 150), and Selysioneiira (fig. 153) 

 it lies before the level of the first antenodals. At the same time 

 Cui becomes shorter and the whole line culminates in Selysioncura 

 (fig. 153), w^hich has only a cross-vein for both Cui and Cuo. In its 

 absence of sectors other than Mia, in the reduction of Cui and Cu2, 

 in the origin of both Rg and M3 beyond the subnodus, in the 

 absence of that portion of A beyond Ac, in the retracted position 

 of Ac, and in the fact that the second antenodals lie before the 

 arculus, this genus presents a combination of characters of so high 

 a degree of specialization that it can hardly be equalled in its 

 reduction by any other member of the Zygoptera. It is therefore 

 fitting that it should be placed at the very apex of the genealogic 



MEM. AM. ENT. SOC, 3. 



