THE SUBFAMILY LIBELLULIN^. 277 



intermediate cells often bisected towards the hind margin, upper sector of the triangle 

 continuous; hind wings broader than the fore wings, with 5 antenodal and 6-8 post- 

 nodal nervures, the first three postnodals not continuous, triangle free, followed by 

 two rows of cells, no supratriangular nervures, one cross nervure in the lower basal 

 cell, sectors of the triangle united at base or rising from a point: anal appendages 

 of male rather short ; legs with numerous slender bristles. 



Type Lihelhda vulgata, Linn. 



Buchecker (Syst. Ent., Odonata, p. 9, 1878) includes Lihelhda flaveola, Linn., depres- 

 siuscula and fonscolomhii, Selys, and three new species in Sympetrum, retaining Dlplax 

 for the remaining European species. However, even if the genus should be subdivided, 

 his employment of the name 8i/mpetrum could not be accepted in this sense, as Newman 

 expressly specifies L. vulgata, Linn, (which Buchecker refers to Diplax), as his type. 



Genus 21. Thec.vdiplax. 

 Selys, Ann. See. Ent. Belg. xsra. p. 140 (1883), xxriii. p. 38 (1884). 



" d . Appendices anals superieurs a pointe plus on moins redressee, le dessous 

 formant une sorte de dent avant la partie terminale, qui est coupee en biseau. 

 Organes genitaux du 2^ segment presque to uj ours saillants. $ . Ecaille vulvaire assez 

 longue, fourchue ou prolongee en lames contigues (rappelaut les Uracis). Les 9' et 10"- 

 segments de consistance moUe comme chez les femelles des Cordulegaster^ 



Type Diplax erotica, Selys. 



Hardly distinct from Syvipetnnn: the pterostigma is moderately long, and the 

 antenodal nervures vary from 7 to 11 on the fore wings. 



Genus 22. Tkithejiis. 

 (Plate LIII. fig. 2.) 

 Brauer, Verb, zool.-bot. Ges. Wien, xviii. pp. 176, .366, 738 (1868). 



Frontal tubercle convex, or slightly depressed in the middle; abdomen moderately 

 slender, sometimes a little thickened at the base, segments 2 and 3 carinated: fore 

 wings with 8-14 antenodal nervures, the last not continuous, and 7-11 postnodal nervures, 

 the first two or three not continuous, cells of the postnodal area simple, pterostigma 

 short or moderate, triangle moderate, on a level with that of the hind wings, traversed, 

 followed by three rows of nervures increasing, or by one or two rows of three, then by 

 several of two increasing, the base hardly oblique, no supratriangular nervures, one 

 cross ner\Tire in the lower basal cell, subtriangular space consisting of three (rarely 

 four) cells, sectors of the arculus stalked, the lower sector a little irregular behind the 

 middle, nodal sector waved at the base, and sometimes slightly in the middle, but 

 usually continuous and nearly straight, subnodal sector continuous, the intermediate 

 cells bisected towards the hind margin ; hind wings much broader than the fore wings, 



