744 M. W. R. de V. GRAHAM 



17 (16) Pronotal collar sharply and evenly margined except just at the sides. Head 



in dorsal view (Text-fig. 613) with temples strongly rounded and from 

 hardly one quarter to slightly more than one quarter as long as eyes. First 

 segment of antennal funicle slightly to distinctly transverse, and usually 

 shorter than the second ......... 38 



Pronotal collar less distinctly and more irregularly margined, or immarginate, 

 when present the transverse carina is sharp at most over about the middle 

 third. Head in dorsal view often with temples relatively longer or less 

 rounded. First segment of antennal funicle sometimes otherwise . . 18 



18 (17) Antennal scape as long or virtually as long as an eye, reaching the level of the 



vertex ; proximal segments of funicle usually quadrate or slightly longer 

 than broad, rarely slightly transverse ; median carina of propodeum weak 

 or absent ............ 19 



Antennal scape distinctly shorter than an eye, often not reaching the vertex ; 

 segments of funicle variable, but sometimes all are transverse ; median 

 carina of propodeum most often distinct and sharp . . . . . 21 



19 (18) Head in dorsal view with temples more than one third as long as eyes. Both 



mandibles with 4 teeth ...... sp. indet. A (p. 756) 



Head in dorsal view (Text-figs. 616, 617) with temples one quarter or slightly 

 more than one quarter as long as eyes. Left mandible (in the specimens 

 examined) with 3 teeth ......... 20 



20 (19) Head in dorsal view (Text-fig. 616) 2-2-2-35 times as broad as long 



micropterus (Lindeman) (p. 766) 



— Head in dorsal view (Text-fig. 617) 2-05-2-15 times as broad as long 



tigasis (Walker) (p. 767) 



21 (18) Head in dorsal view (Text-figs. 618, 620-623, 625) with temples one third as 



long as eyes or more .......... 22 



- Head in dorsal view (Text-figs. 613, 624, 626, 628) with temples one quarter 



as long as eyes or less .......... 34 



22 (21) Head of characteristic shape ; in frontal view (Text-fig. 619) with lower 



margins of oral fossa, on either side of the clypeus, distinctly curved and 

 projecting slightly below the level of the front margin of the clypeus ; in 

 dorsal view (Text-fig. 618) only 1-8-1-85 times as broad as long, with 

 temples fully half as long as eyes ..... genalis sp. n. (p. 757) 

 Head in frontal view with lower margins of oral fossa not or hardly curved, 

 and not projecting distinctly below the level of the front margin of the 

 clypeus ; in dorsal view (Text-figs. 620-623, 625) twice or slightly more 

 than twice as broad as long, with temples at most barely half as long as eyes 23 



23 (22) Antennae (Text-fig. 634) with all funicular segments at least slightly transverse. 



Relatively small species, rarely over 2 mm. in length, and not more than 



23 mm. ............ 24 



Antennae (Text-figs. 632, 636, 640) with at most segments 3-6 of the funicle 



transverse. Species sometimes relatively larger (length 1-7-3-3 mm.) . 27 



24 (23) Scutellum somewhat flattened discally, its reticulation only very slightly 



raised above the general surface ; both it and the mesoscutum relatively 

 shiny. Left mandible with 3 teeth, right mandible with 4 sp. indet. H (p. 775) 

 Scutellum moderately convex, its reticulation distinctly raised above the 

 general surface ; both it and the mesoscutum relatively less shiny. Both 

 mandibles with 4 teeth ......... 25 



25 (24) North American species. Median area of propodeum (Text-fig. 605) about 



1-7 times as broad as long. Mesoscutum somewhat more than twice as 

 broad as long. Scutellum slightly longer than the mesoscutum. Antennal 

 scape not nearly reaching the median ocellus. 



