08 Journal New York Entomological Society. [Voi. xi. 



Lateral ocelli not close to the eye margin ; club of antennce 5-jointed. 



TrichaciS Forster (type Platygasler pesis WALKER ). 



13. Abdomen not much lengthened 14 



Abdomen very much lengthened. 



Club of antenna- 5-iointed ; mesonotal lines distinct. 



Poly meCUS Forster ( partim ) . 



14. Lateral margins of the abdomen normal 15 



Lateral margins of the abdomen broadly deflexed. 



Mesonotal furrows distinct Hypocampsis Forster. 



(type H. /lyaHnata Thomson), 



15. Thorax short, the scutellum pillow-shaped, separated from the mesonotum by a 



deep furrow 16 



Thorax more elongate, the scutellum not separated from the mesonotum by a 

 deep furrow ; mesonotal furrows distinct 17 



16. Face with a distinct keel between the antenna Eritrissomerus Ashmead. 



(type E. cecidomyiiL AsHM. ). 



Face without a keel between the antenna Polygnotus Forster. 



(type Platygaster striolata Nees). 



17. Lateral ocelli nearer the eye margin than to the front ocellus. 



Platygaster Latreille (type P. rufipes Latr. ) 

 Lateral ocelli nearer the front ocellus than to the eye margin. 



Isocybus Forster (type Platygaster grandis Nees). 



18. Scutellum lengthened, never semicircular ; if shortened it is compressed at the 



sides and furnished with an awl-shaped thorn or tubercle 19 



Scutellum not lengthened, semicircular, or either flat, convex or cushion- 

 shaped 25 



19. Scutellum lengthened, triangular, often produced into. a long, acute spine 20 



Scutellum not lengthened, with an awl-shaped thorn, short thorn or tubercle. 22 



20. Thorax not strongly compressed from the sides 21 



Thorax strongly compressed from the sides. 



Head large, rounded or quadrate Piestopleura Forster. 



21. Mesonotal furrows deep, parallel posteriorly Xestonotus Forster. 



Mesonotal furrows at most feebly impressed or wanting. ...Amblyaspis Forster. 



22. Scutellum with a short thorn or tubercle at apex 23 



Scutellum with a strong awl-shaped thorn at apex. 



Lateral ocelli nearer the eye margin than to the front ocellus. 



LaptaciS Forster. 



Lateral ocelli nearer the front ocellus than to the eye margin or not nearer 



to the eye margin than to the front ocellus Isorhombus Forster. 



23. Abdomen not much lengthened 24 



Abdomen much lengthened, longer than the head and thorax united, the second 



segment very large. 

 First joint of flagellum minute, rounded, the second large, dilated. 



PoIygmecuS Forster. 



24. Ocelli their width from the eye margin Sactogaster Forster. 



Ocelli close to the eye margin Synopeas Forster. 



25. Scutellum not cupuliform, convex or flattened 26 



