THE SUBFAMILY LIBELLULIN^E. 273 



neuration not unusually close ; fore wings with the costa a little swollen at one 

 fourth of its length, which is followed by a more or less distinctly marked concavity 

 about halfway between the base and the nodus ; 11-15 antenodal and 5-9 postnodal 

 nervures, the last antenodal generally not continuous, and the first two or three post- 

 nodals not continuous, cells of the costal areas simple ; triangle large, placed hardly 

 beyond that of the hind wings, crossed by 1-3 nervures, and followed by 3-6 rows of 

 cells, supratriangular nervures (1-3) present or absent ; subtriangular space consisting 

 of 3-7 cells, sectors of the arculus stalked (or rarely separated on the fore wings), 

 lower basal cell empty or traversed, nodal sector continuous, bat slightly waved, 

 subnodal sector and lower sector of the arculus continuous, space between the nodal 

 and subnodal sectors more or less bisected at the extremity ; hind wings about as long 

 as the fore wings, and not much broader, with 7-8 antenodal and 5-7 postnodal cellSj 

 the first two or three of the latter not continuous ; the triangle traversed by one 

 nervure (sometimes two), one or two cross nervures in the lower basal cell (occasionally 

 four) ; a supratriangular nervure occasionally present, triangle followed by two to three 

 rows of cells, its sectors rising from a point : anal appendages moderate. 



Type Palpopleura vestita, Eamb. 



The variations in neuration between specimens of the same species are very great in 

 this genus, and but little importance can be attached to them. That of a specimen of 

 P.jucunda, Ramb., is figured. The sinuation of the costa in the Chinese P. sexma- 

 culata, Fabr., is so slight as to be sometimes hardly perceptible. 



Genus 15. Perithemis. 

 (Plate LI. figs. 7, 8, 9.) 

 Hagen, Neur. N. Amer. p. 185 (1861); Brauer, Verh. zool.-bot. Ges. Wien, xviii. pp. 365, 718 

 (1868). 



Frontal tubercle rounded; eyes contiguous in front; abdomen moderately stout, 

 with the sides nearly parallel, or rather broad in the middle, tapering at each 

 extremity, and somewhat depressed, shorter than the hind wings; segments 2-4 

 transversely carinated, segment 8 not perfoliate in the female ; pterostigma moderately 

 long, and generally rather thick ; fore wings with 7-8 antenodal and 4-6 postnodal 

 nervures, the last antenodal and the first one to three postnodals not continuous, cells 

 of the costal area simple, triangle broad, the upper and basal sides nearly equal, free, 

 or traversed by one or two nervures, followed by two (rarely three or four) cells ; no 

 supratriangular nervures, subtriangular space consisting of 1-3 cells, sectors of the 

 arculus separated, or rising from a short stalk, the lower sector continuous, and only 

 o-radually curved, lower basal cell with one cross nervure, nodal and subnodal sectors 

 continuous, the former arched, the two last intermediate cells only divided; hind 

 wino-s slightly broader than the fore wings, with 5-6 antenodal and 4-5 postnodal 

 nervures, the first one or two of the latter not continuous, triangle traversed or free, 



vol. xn. — pabt ix. No. 4. — August, 1889. 2 s 



