126 



EAST AFRICAN ODONATA-CALVEET. 



VOL. XVIII. 



of the arculus stalked; one cross vein in the median space/ j)laced 

 nearer the base than the first antecnbital; no hyi^ertrigonals; nodal 

 sector aluiost straight. Front wings with 10-12 antecubitals, the last 

 one not continuons, 6-9 i^ostcubitais ; triangle with one cross vein; 

 internal triangle of three cells, three rows of posttriaugular cells. 

 Hind wings with 8-9 antecnbitals, 7-10 postcnbitals, triangle free, no 

 internal triangle, two rows of posttriangnlar cells, sectors of the tri- 

 angle arising from the same point.'^ 



Female. — Vertex and frons shaped as in male, luteons. Occiput dark 

 brown. Nasus, rhinarinm and lips yellow. Eear of head, thorax, feet 

 and abdomen luteons. Hind margin of prothorax slightly truncate, 

 with a trace of a median emargination. Thorax paler on the sides. 

 Abdomen with black marks similar to those of male. Appendages 

 simple, straight, luteons, not quite as long as 9. Vulvar lamina j^ro- 

 duced a little beyond the apex of 10, its margin entire; apex rounded. 

 Wings similar to those of male; basal ferrugineous si^ot on hind wings 

 not extending as far toward the posterior margin. Front wings with 

 10-11 antecubitals, 8-9 postcnbitals. Hind wings with 8-9 antecnbi- 

 tals, 7-9 postcnbitals.^ 



Measurements of Trithemis f err ug aria. 



Total lengtli 

 Abdomen*.. 

 Front wing. 

 Hind wing.. 

 Pierostigma 



* Here, a.s always, I include the appendages. 



Rambur has described only the male of this species. His description 

 is mainly comparative, noting the differences from T. erythra'ci, Brulle 

 (T.ferruginea, Vander Linden) as follows: 



A little smaller than T. ferruffinea, resembliug it extremely; of a lighter color, 

 red, depending on the age. Head having the face and the vertex a little less pro- 

 jecting. Posterior lobe of the prothorax sensibly projecting, slightly notched in 

 the middle (projecting in T. ferruglnea). Abdomen much less broad, less depressed, 

 trigonal, narrow posteriorly, reddish, having small, black, long, and narrow spots 



'Variations: One male has two such median cross veins in left front wing and in 

 both hind wings, and has triangle of right hind wing with one cross vein. Another 

 male has two median cross veins in right hind wing, and the triangle of left hind 

 wing with one cross vein. A third male has two median cross veins on left hind 

 wing. A fourth male has both hind wings with two median cross veins. The 

 additional median cross vein is always on the outer (apical) side of the normal. 



-Variation: On right hind wing of one male the upper sector of the triangle 

 arises from the lower sector a short distance from the origin of the latter. 



^Variations in venation of these two females; One has right hind wing with tri- 

 angle having one cross vein, and both hind wings with the sectors of the triangle 

 separated a short distance at their origins. The other has the left hind wing with 

 two median cross veins. 



