^^iSD^''] PROCEEDINGS OP THE NATIONAL MUSEUM. 583 



brown spot ; a browu dot ou each side of tho median dorsal line near the apex of 3 to 

 6, sometimes also on 7 and 8 ; 2 and 3, only, with a transverse carina. 



Genitalia not prominent. Hamnle bifid, internal branch terminating in a small, 

 rather acute hook directed outwards; external branch much thicker; apex obtnse. 

 Genital lobe with apex rounded, hairy. 



Appendages brownish yellow, with short hairs. 

 Superiors of about the length of the eighth seg- 

 ment; viewed from .above, they are straight, dilated 

 on the inner side before the apex, which is acute, 

 black ; viewed from the side, they are directed 

 slightly downwards to the extreme apex, which in- 

 clines slightly upwards (as in vnlgata) ; on the under 

 side are 9 to 13 black denticles corresponding in 



position to the dilatation on the inner side. Inferior ^, .^ ,. „ ,^. '' ', ^ ^ . 



. Genitalia of Diplax dilatatac^ n. sp. 



appendage, viewed from the side, is concave above 



from base to apex, which latter is curved upwards and ends in a small black denticle 



on each side ; this denticle extends a little beyond the last denticle on the under 



side of the superiors; viewed from below, the appendage is rather broad, triangular, 



apex truncated, slightly emarginate. 



Wings hyaline, reticulation brownish, hind wings with a light yellow cloud 

 alongside of the membranule, extending outwards to about the level of the basilar 

 cross vein, and backwards but little farther than the apex of the membranule. 

 Pterostigma 3 to 4 times as long as broad, brownish yellow, surmounting parts of 

 two or three cells. Membranule moderate, whitish. Sectors of the arculus stalked. 

 One basilar cross vein placed nearer the base than the first autecubital. Nodal 

 sector slightly waved. No hypertrigouals. Front wings with 10 (occasionally 9 in 

 one wing) autecubitals, the last not continuous; 10 to 12 postcubitals ; discoidal 

 triangle with one or two cross A'eins; internal triangle of 4 to 6 cells; four, then 

 three rows of discoidal areolets. Hind wings with 7 antecubitals, the last continu- 

 ous; 10 to 12 postcubitals; discoidal triangle free, its inner side in the prolongation 

 of the arculus; no internal triangle; discoidal areolets three, then two rows in- 

 creasing; sectors of the triangle arising from the same point. 



One male differs in having an additional basilar cross vein placed so as almost to 

 form ail internal triangle ou the right hind wing, an indication of the Iteginuiug of 

 such a vein on the left hind wing, both hind wings with discoidal triangle crossed 

 by one vein. 



9- Similar to the male; dift'ers as follows: Lobes of the labium yellow, mar- 

 gined as in <?. The first three segments of the abdomeu yellow; 1 black at base, 2 

 and 3 brownish along the median dorsal line; a crooked brown stripe on the sides of 

 1 to 3; venter of 2 and 3 black. Remaining segments of abdomeu lost. 



Nine antecubitals to the front wings, last one on the right wing having a corre- 

 sponding cross vein in the subcostal si)ace although not continuous. Riyht-hand 

 wing with 6 antecubitals. Two discoidal areolets at the triangle in hind wings. 



Measurements: $» Total length, 44. .5 to 47.5 millimeters. Abdomen (inch app.), 

 2G.5 to 31.5 millimeters. Superior ai)pendages, 1.75 to 2 millimeters. Front wing, 

 35.5 to 37 millimeters. Hiiid wing, 33 to 34.5 millimeters. Pterostigma, 3.5 to 4 

 millimeters. Width of alulomen at base of 5, 1.5 niillimeters. Width of abdomen 

 at 7, 3 to 4 millimeters. 



9. Length, abdomen, appendages, ?. Front wing, 37.5 millimeters. Hind wing, 

 34.5 millimeters. Pterostigma, 3.5 millimeters. 



Four males, one female from St. Helena. Dr. Hagen examined one of the males 

 forme and wrote, "It is unknown to me." This species belongs to the group of 

 genera embracing DipJax, Thecadiplax, and Erythrodiplax in Dr. Karsch's arrange- 

 ment of the Libellulina (Berliner Ent. Zeit., xxxiil, pp. 347-392, 1890). I place it 

 provisionally in Diplax. 



