190 CHARLES ROBERTSON. 



9. Enclosure distinctly defined, with sharp ridges; abdomen fasciate, margins of 



segments pale testaceous claytonise. 



Enclosure less distinctly defined, rough but without sharp ridges; abdomen 

 without fasciae, black crateegi. 



MALES. 



Angles of ventral segment 6 refiexed cratsegi. 



Angles of ventral segment 6 simple 1. 



1. Joint 3 = 4, or nearly ; abdomen usually more or less reddish marise. 



Joint 3 shorter than 4, abdomen black 2. 



2. Segment 2 depressed less than one-half 5. 



Segment 2 depressed at least one one-half 3. 



3. Hiud tibia reddish hippotes. 



Hind tibia black 4. 



4. Pubescence uioi-e dense ; abdomen distinctly punctured rugosa. 



Pubescence less dense ; abdomen almost impunctate spirseana. 



5. Segment2depressed less than one-half; antennasmooth and shining. ..forbesii. 

 Segment 2 depressed one-third ; insect feebly ])unctured ; flagellum moniliform. 



claytonise. 

 ANDRKiVA F. 



FEMALES. 



Abdomen not red 2. 



Abdomen red 1- 



1. Head and thorax greenish ; scutel purplish ; length 7-8 mm. ; enclosure broad. 



illinoensis bicolor. 

 Head and thorax black; length 10-11 mm. ; cheeks broad. • .erythrogastra. 



2. Tibial scopa pale 5. 



Tibial scopa largely black. 3. 



3. Pubescence black, except on thorax above, vertex, and sometimes middle of face. 



carlini 

 Pubescence not black ; tibial scopa black on posterior edge 4. 



4. Abdomen bare; pubescence ochraceous; cells III5 and III4 subequal ; joint 



3 longer thau 4-|- 5; fovea extending below antenna • .violniformis. 



Abdomen with long pubescence, subfasciate; pubescence griseous ; cell III4 



one-third longer than III5 ; joint 3 about = 4-6 ; fovea not extending 



below antenna erythronii. 



5. Abdomen without bluish or greenish tinge 8. 



Abdomen with bluish or greenish tinge, finely roughened, impunctate, or 



nearly, thinly fasciate ; small species 6. 



6. Vein IV3 arising before middle of cell Ills; stigma dark; abdomen bluish; 



hind tibia and tarsus subequal geranii. 



Vein IV3 arising at or beyond middle of cell Ills ; stigma pale; abdomen 

 greenish ; smaller species 7. 



7. Scutel purplish ; enclosure broad ; slender species illinoensis. 



Scutel not purplish ; enclosure ordinary ; less slender species polemonii. 



8. Hind tibia cuneate, apex twice as broad as metatarsus, outer face with short 



hair; enclosure broad, rugose; segments 1-2 opake, finely roughened ; 

 with shallow punctures; fovea broad, extending below base of cly- 



peus; joints = 4 -f .5 nasonii. 



Hind tibia at apex less than twice as broad as metatarsus 9. 



