1913.] NATURAL SCIENCES OF PHILADELPHIA. 261 



ZZ. — Supplementary sectors from Mia to 



Cui 



Meiacjrion n. gen.^^ (New Guinea). 

 YY. — Area posterior to Cu2 with one row of 

 cells, no supplementary sector pos- 

 terior to M3. 

 a. — Quadrilateral not touching the hind 

 margin of the wing, supplementary 

 sectors between ^Mia and ]M2 and 



between Rs and AIs 



Mesagrion Selys, 1885 (Colombia). 

 aa. — Quadrilateral touching the hind 

 margin of the wing, no supple- 

 mentary sectors except a rudiment 

 between ]\I2 and Rs or between Rs 

 and Ma, arculus well distal to the 



second antenodal 



Perilestes Belys, 1862 

 (Costa Rica, Guiana, Brazil). 



In view of the olDservations on the imperfection of our knowledge, 

 made on p. 256, in introducing the preceding Synopsis, it seems 

 useful to offer also this 



Outline of an Alternative Grouping of the Genera of the 

 Legion Podagrion. 



A. — Area posterior to Cu2 with more than one row of cells. 



B. — A separating from the hind margin proximad to the level 



of the arculus, Ms separating from Mi-r2 proximad to the 



subnodus. 



C. — Rs beginning proximad to the subnodus, two antenodals, 



supplementary sectors Mia to M4, two rows of cells 



posterior to Cu2 Melanagrion. 



CC. — Rs beginning at the subnodus, more than two ante- 

 nodals Dysagrion, Phenacokstes, Thatimatoneura. 



BB. — A separating from the hind margin at, or distad to, the level 

 of the arculus, normally two antenodals. 

 D. — Ms separating from Mi+o proximad to the subnodus. 

 E. — Rs beginning at the sulinodus . Podopterijx,Argiolestes. 



EE. — Rs beginning distad to the subnodus 



Paraphlebia hyalina. 

 DD. — Ms separating from M1+2 at, or distad to, the level of 



the subnodus Paraphlebia, Wahnesia, Metagrion. 



AA. — Area posterior to Cu2 with onlj- one row of cells. 



F. — A separating from the hind margin proximad to 

 the level of the arculus. 



3^ Type: Argiolestes postnodalis Selys. This genus is group lA of Selys' 

 Revision of 1886, p. 81. 



