32 GENERA OF HYMENOPTERA, 



•24. — Base of scntellum, ininiefliately at the thickened terior margin, with two 

 8inall transverse fovere, or better with a si,. .ill and short transverse 

 groove, feebly interrupted medially, and separated externally by a lon- 

 gitudinal carina from the very variable triangular lateral fovea, these 

 two longitudinal ridges are not, as usual, parallel, but diverge posteri- 

 orly ; antenna' 14-.jointed. long and slender, third joint twice, or nearly 



twice, as long as fourth ; lin Compositte gMs) 5. *Timaspis Mayr. 



Base of scntellum with two very sharply separated fovese, which are more 

 or less triangular or (juadrangular, and often very large ; the large tri- 

 angular lateral fovea not extending upwards and inwards, but lies on the 

 free side of scutelluni ; antennre 13-14-jointed, third joint shorter, or a 

 little longer, than fourth ; marginal cell short, or moderately long, in the 

 last case the third antennal joint is no longer than fourth ; (in galls of 

 various herl)s and bush-like plants) 7. *Aulax Hartig. 



•2.5. — Base of scntellum with two sharply separated fovese ; metathorax with 

 straight, parallel ridges, rarely distinctly, but not sharply serrulate, or 

 inferiorly somewhat divergent (as in many European agamous forms); 

 parapsidal grooves sharp and entire, often indistinctly defined anteriorly, 

 mesothorax rarely transversely wrinkled ; antennte and tibise not fim- 

 briate ; third joint of antennse longer than fourth ; these joints are equal 



in the American A. tuhicola ; (in Oak-galls) 17. Andricus Hartig. 



Otherwise formed ; metathoracic ridges (except in Loxaulua) not straight 

 and parallel ; base of scutelluni with a transverse furrow, or with two 

 sharply limited fovete ; in the last case the metiithoracic ridges in the 

 middle elevation of metathorax are strongly arcuate or angularly sepa- 

 rated 26. 



•26. — ('laws of jiosterior tarei entire ; antennte and tibite not fimbriate ; me.sotho- 



rax glabrous 87. 



Claws of posterior tarsi bidentate ; mesothorax often abundantly hairy ; 

 scutelluni usually with an uninterrupted transverse groove 30. 



27. — Para^eidal grooves of the poli.slied or moderately deeply wrinkled meso- 

 thorax very sharply defined ; antennte with 14-1.5 free joints, the third 



as long, or longer than fourth 28. 



Parapsidal grooves of the alutaceous mesothorax shallow, feebly or not at 

 all impressed anteriorly ; antennre with 13-14 free joints, third and 

 fourth equal ; middle area of metathorax with a more or less distinct 

 median longitudinal carina 29. 



28. — Base of scutellum with two distinctly sejiarated fovese; the moderately 

 thick aiitcunie with 14 free joints; mesothorax polished; body yellow 



or reddish yellow; (in Oak-galls) 22. Biorhiza Westw. 



Base of scntellum with a broad transverae groove ; the not thick antennae 

 14-15-jointed ; (in Oak-galls) 26. ''Dryocosinus Gir. 



29. — Cheeks without any, or only a feeble groove; antennse 14-jointed ; head not 

 broader behind the eyes ; scntellum at base with two fovese ; metathorax 

 with two median, angular, divergent ridges ; (in Oak-galls). 



24. *Plagriotrochu8 Mayr. 



Cheeks with a sharp furrow ; antennse with 13 shar|)ly defined joints; head 



distinctly broader behind the eyes; base of scutellum with an arcuate 



tr.msverse groove; metathoracic ridges almost straight and parallel ; (in 



X. Am. Oak-galls) 2."). Loxaulus Mayr. 



