56 A VENATIONAL STUDY OF THE ZYGOPTERA 



30 (31). Tarsal claws symmetrically cleft, so that the superior and inferior teeth are 

 about equal. The ninth segment of the abdomen almost equals the eighth. The 

 first segment of the antenna scarcely visible; superior male appendages as long 

 as the inferior. Malaysia Onychargia Selys, 1865 



31 (30). Tarsal claws not symmetrically cleft, the superior and inferior teeth not 

 equal 32 



?)2 (33). The area posterior to Cu2 tends to be two cells wide and the second anteno- 

 dal is often slightly beyond the level of the arculus. M4 becomes zigzag at the 

 level of the fork of M 1+2. Mexico to Colombia. (Fig. 82.) 



Hyponeura Selys, 1854 



33 (32)- The area back of Cu2 of one row of cells only 34 



34 (35)- The prolongation of the nodal cross-vein through the vein M1+2 is generally 

 at first perpendicular to Mi+2- Mi+o in the front wing forks six cells beyond the 

 subnodus; in the hind wings four cells beyond. Tibial spines three times as long 

 as the intervening spaces. New Guinea. (Fig. 83.) Palaiargia Foerster, 1903 



35 (34)- The prolongation of the nodal cross- vein through the vein Mi-1-2 is not per- 

 pendicular to Mi+2 36 



36 (37)- Cua long, extending to Ihe level of the origin of Mia, especially in the hind 

 wing, and at least ten or twelve cells beyond the subnodus. Generalh- fourteen 

 or more postnodal cells; three to seven antenodal cells between M4 and Cui. 

 The New World. Moluccas, Cape of Good Hope. Kurile Islands. (Fig. 84.) 



Argia Rambur, 1842 



37 (36)- Cu2 short, not extending more than four or five cells beyond the level of the 

 subnodus. About ten cells present between the nodus and the stigma 38 



38 (39)- An apical spine on segment eight of the female. The arculus slightly be- 

 yond the second antenodal. Three antenodal cells between M4 and Cui. West 

 Indies and Central America. (Fig. 86.) Argiallagma Selys, 1876 



39 (38). No apical spine on segment eight of the female. The arculus at the second 

 antenodal. Two antenodal cells between M 4 and Cui. Brazil. (Fig. 85.) 



Diargia Calvert, 1909 



40 (29). Tibial spines shorter, scarcely longer than the intervening spaces; if long, 

 the wings are petioled to or beyond Ac. The inner end of the quadrangle usually 

 not longer than the upper part of the arculus in the fore wing, nor longer than the 

 upper side of the quadrangle. Quadrangle generally not widened distally ..... 41 



41 (88). No pale post-ocular spots present on a dark background 42 



42 (53). Female with apical spine on segment eight-" 43 



(A) Wing petioled to the vein Ac. The quadrangle in the front wing with a very pointed 

 distal lower angle, so that the upper side is shorter than or only as long as the inner 

 end. Tenth segment of the abdomen with a deeply cut posterior margin. Con- 

 siderable blue in the coloration. South America. (Fig. 121.) 



Skiallagma Foerster, 1906 



^^ The following two genera cannot be fitted into the key, because the females are un- 

 known, but a brief description may aid in their determination. 



