8 U. S. NATIONAL MUSEUM BULLETIN 216 



Second abdominal tergite without median longitudinal carinae; second re- 

 current vein meeting cubitus considerably before the intercubitus, the 

 second abcissa of cubitus being more than 0.3 as long as intercubitus; 

 metapleurum usually bare or with only a few hairs; temple rather long . 17 



16. First abdominal tergite in profile evenly convex (fig. 176,b) ; epipleura of 



fifth and sixth abdominal segments weakly or indistinctly separated from 

 their tergites; subtegular ridge rounded, in rear view with an excavation 

 that makes it appear to be folded over. Nearctic. 



12. Bothromus (p. 142) 



First abdominal tergite in profile pyramidal (fig. 173, a); epipleura of fifth 



and sixth abdominal segments sharply separated and sharply folded under; 



subtegular ridge sharp, without an appearance of being folded over. Old 



World 13. Drcpanoctonus (p. 145) 



17. Interantennal process of face separated from face by a prominent transverse 



carina (fig. 177,a); lower half of propleurum subspherically swollen (fig. 



177,a). Holarctic and Oriental 19. Stethoncus (p. 167) 



Interantennal process of face not separated from face by a carina (figs. 175; 

 176,a; 177,b) 18 



18. Back of head vertical behind posterior ocelli (fig. 176,a) ; face in profile sloping 



forward to its upper margin; spurs of middle tibia of approximately equal 



length. Worldwide 18. Hypsicera (p. 160) 



Back of head sloping from posterior ocelli to the level of the occipital carina, 

 thence approximately vertical to the foramen magnum 19 



19. Epipleurum of third tergite very narrow, about as wide as the flagellum; 



cheek about 0.8 as long as the mouth opening is wide (fig. 175,a); spurs of 

 middle tibia of approximately equal length. Nearctic. 



17. Macromalon (p. 158) 



Epipleurum of third tergite well developed, about 0.25 to 0.7 as wide as its 



tergite; cheek not more than 0.5 as long as the mouth opening is wide; 



spurs of middle tibia unequal in length 20 



20. Front spur of middle tibia longer than hind spur of middle tibia; median 



longitudinal carinae of propodeum approximate or fused medially, re- 

 sulting in the basal area and areola being well separated (fig. 175,b) ; 

 interantennal process of face weakly notched at apex (fig. 175,b). Nearctic. 



20. Synosis (p. 169) 



Front spur of middle tibia shorter than hind spur of middle tibia (except in 



one Australian species) ; median longitudinal carinae of propodeum, when 



present, not approximate or fused medially (fig. 188,a-k); interantennal 



process of face nearly always pointed medially (fig. 179,g-o). Worldwide. 



21. Exochus (p. 170) 



1. Genus Pseudometopius 



Figure 164, a 



Pseudometopius Davis, 1897, Trans. Amer. Ent. Soc, vol. 24, .p. 202. Type: 



Metopius hogenii Cresson; monobasic. 

 Tylocomnoides Uchida, 1940, Trans. Sapporo Nat. Hist. Soc, vol. 16, p. 178. 



Type: Tylocomnoides egawai Uchida; original designation. 

 Odontotylocomnus Uchida, 1940, Trans. Sapporo Nat. Hist. Soc, vol. 16, p. 179. 



Type: Odontotylocomnus pilosus Uchida; original designation. 



Front wing 8 to 10.5 mm. long; body punctation rather strong; 

 face and clypeus weakly convex, with surface irregularities; face con- 



