1913.] NATURAL SCIENCES OF PHILADELPHIA. 265 



by Mr. Campion in his preceding paper on "The Antenodal Reticu- 

 lation of the wings of Agrionine Dragonflies."^"^ 



Additional Data on Dimeragrion n. gen. 



In addition to the venational characters which have been given 

 on pp. 238-239, anted, the following are generic features from other 

 parts of the body: 



Second antennal joint one and one-half times as long as the first, 

 the third longer than the first two together. 



Ligula (median labial lobe) bilobed in its distal third, apices 

 tapering but not very acute, separated by an interval whose width 

 is about equal to its depth. 



Tibial spines longer (often 2-3 times longer) than the intervals 

 separating them, 7-8 in the anterior (outer) row, and 8-9 in the pos- 

 terior (inner) row of the third tibia. 



The generic name proposed is in allusion to the fact that there are 

 two supplementary sectors onl}^ in two areas of the "vv^ng, viz., those 

 between Mio and M2 and between Rs and Ms. 



Type, Dimeragrion percubitale n. sp. 

 Dimeragrion percubitale n. sp. PI. XIV, figs. 6-S. 



Adult cf . — Vertex, genae, and rear of the head black with some 

 metallic green reflection not very brilliant. A yellowish streak 

 between each antenna and the lateral ocellus of the same side. 

 Traces of pruinosity on the rear of the head. Frons, nasus, and upper 

 half of rhinarium dark metallic violet, well-defined from the black 

 above and the pale yellow below, which latter forms a transverse 

 band on the lower half of the rhinarium and basal half of the labrum, 

 this band having almost parallel edges. Distal half of the labrum 

 and the mandibles dark metallic violet. Submentum, mentum, and 

 bases of the maxillse luteous, the distal parts of these two pairs of 

 appendages blackish. Antennae black. 



Prothorax black with a slight metallic green reflection. 



Mesepisterna and mesepimera metallic green, low^er part (more 

 than half) of the former and the third fourth (counting from above) 

 of the latter pruinose, or the latter without pruinosity. Metepi- 

 sternum metallic green or metallic violet, a narrow pale (luteous ?) 

 stripe separating this color from that of the mesepimeron, or this pale 

 stripe absent (still older males). Metepimeron and metasternum 

 pale brown or luteous, some pruinosity on the latter. 



"1 These Proceedings, anted, pp. 220-224. 



