42 A VENATIONAL STUDY OF THE ZYGOPTERA 



Key to the Genera of the Subfamily Polythorinae 



1 (8). Cu2 branched, more than one row of cells between Cui and Cu2 and between 

 Cu2 and the wing-margin 2 



2 (7)- Quadrangle of hind-wing one and one-half to two times as long as that of the 

 fore-wing. Wings petioled about one-half of the way to the arculus. Fore-wing 

 about three and one-half times as long as broad. Cu2 forking, with two rows of 

 cells between the branches. Arculus at slightly more than one-third of the dis- 

 tance from the base of the wing to the subnodus 3 



3 (6). Fore and hind wings of same general shape and size. Sectors arising between 

 the main veins, which do not appear forked. M2 arising within a cell or two of 

 the subnodus 4 



4 (5)- Venation very complex, many sectors and cross-veins; for example, 40-50 

 antenodals; often 12 or more cross-veins under the stigma; rather prominent 

 sectors between M4 and Cui, at least in the hind wing. In the hind wing, several 

 sectors between M2 and Rs arise as far proximad as the inner end of the stigma. 

 Northern South America from Colombia to Peru and Brazil. - (Fig. 2.) 



Polythore'' Cahert, 1917 

 {Thore Selys, 1853) 



5 (4). Venation not so complex, antenodals 20 to 35; cross-veins under the stigma 

 6 to 10; usually no sectors between M4 and Cui, more than three or four cells 

 long. Between M2 and Rs no sectors arise proximad of stigma. South America, 

 Venezuela to Peru and Brazil. (Fig. 3.) Eu thore Selys, 1869 



6 (3). Fore-wing evidently longer and narrower than the hind wing. Main veins 

 appear forked because of the attached sectors. M2 arising two to four cells be- 

 yond the subnodus, especially in the fore-wing. Brazil. (Fig. 4.) 



Chalcopteryx Selys, 1853 



7 (2). Quadrangle of hind wing scarcely longer than that of the fore wing. Wings 

 petioled about two-thirds of the distance from the base of the wing to the arculus. 

 Fore wing about four and one-half times as long as broad. Arculus often at almost 

 one-half the distance from the wing-base to the subnodus. Mexico to Bolivia. 

 (Fig. 5-) Cora Selys, 1853 



8 (i). Cu2 unbranched, one row of cells between Cui, and Cu2, one row of cells back 

 of Cu2 Miocora Calvert, 1917 



Key to the Genera of the Subfamily Agrioninae 



1 (24). Cu2a present. Rs in hind wing usually strongly waved 2 



2 (19). Cu2a running perpendicular to the posterior margin of the wing or toward the 

 base of the wing, and usually with one or more sectors toward the anal angle 

 which are longer than the quadrangle 3 



3 (12). In the hind wing the sectors of that portion of the wing posterior to Cuo 

 and distad to Cu2a are generally arched from near the wing margin and not di- 

 rectly attached to Cu2a. True stigma present 4 



* Calvert, 1917, proposes the name Polythore for this genus, since the name Thore 

 is preoccupied. 



