74 burmeister's odonata. 



beyond the fienticles of tlie superiors, hardly loiifier than it is wide at base, its 

 tip one-fourth to one-third as wide as base, with the usual two upturned denticles. 



Genitalia of abdominal segment 2: Anterior lamina inconspicuous, its margin 

 entire. Apex of hamule bifid, inner branch slender, curved to form a hook, outer 

 branch twice as long and as thick, its tip rounded. Genital lobe a little more 

 prominent than the hamule, about one-and-a-half times as long as wide, tip 

 rounded. (PI. I, tig. 5). 



Wings slightly smoky throughout, reticulation black. Pterostigma reddish- 

 brown, surmounting one cell and parts of two others. Membranule blackish. 

 Upper end of arculus at the second antenodal or slightly nearer, its sectors 

 stalked, nodal sector not waved, supplementary sector next below the suhnodal 

 separated from it by but one row of cells. All discoidal triangles with one cross- 

 vein. No hypertrigonals. 



Front wings: 12-14 antenodals, the last not continnous, 8-10 postnodals. one 

 suhmedian cross-vein nearly on a level with the first antenodal, internal triangle 

 of three cells, three posttriangular cells for one cell (two wings) or two cells (two 

 wings) then two rows to the level of the origin of the subnodal sector increasing 

 to six marginal cells. Brownish yellow at base reaching to suhmedian cross-vein 

 or not quite so far. 



Hind wings: 9-10 antenodals, 9-10 postnodals, two suhmedian cross-veins, 

 two posttriangular rows (between short sector and first sector of triangle) to the 

 level of the separation of the median sector increasing to 9-11 marginal cells 

 sectors of the triangle a little separated at origin. Brownish yellow at base, 

 reaching out to the first antenodal but not attaining the hind margin of the wing 

 by one-fourth of the width of the wing. 



Total length 32. Abd. 20. F. W. 28. H. W. 27. Pter. 3. Sup. app. 1.5 hind 

 tibia 5. 



The systematic importance of two neurational details which are 

 symmetrically developed on these two types: the hind wings having 

 a cross- vein in the discoidal triangle and two suhmedian cross- veins 

 is diminished by the circumstance that in the Mus. Comp. Zool. are 

 two males in which I can discover no specific difference from castanea, 

 one of w'hich has the triangles of both hind wings with a cross- vein, 

 one suhmedian cross-vein on the right side, two on the left, while 

 the other male has these triangles free and but one suhmedian cross- 

 vein on each side. A third male agrees with castanea types in these 

 regards, as does a male in my collection. Of three females in the 

 Mus. C. Z. which seen! to belong to this species, one has the trian- 

 gles free, two have them crossed on both sides, two have two sub- 

 median cross-veins on one side only, one has but one suhmedian 

 cross-vein on each side, a female in my own collection has the triangle 

 free and two suhmedian cross veins each side— these statements re- 

 ferring to tlie hind wings onlv. 



