40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. Ill 



Urogomphi with tips of outer prongs either bluntly rounded (opr, figs. 

 13, g; 14, /) ; or sharp and inclined upward, inward or forward 

 (figs. 13, c; 14, i) ; without spinelike setae (usually with a few very 

 fine setae) on episterna of mesothorax and metathorax; abdominal 

 mediotergites with prominent posterior setae not definitely "paired" 

 (fig. 14, d) (species primarily predaceous) 7 



4. Prongs of each urogomphus like grappling hooks (fig. 13, e) ; eyes 



usually small and indistinct 5 



Urogomphal prongs of different type (fig. 13, d, f) ; eyes usually 



clearly visible 6 



5. Pleurites in first abdominal segment practically as long as sternal 



plate semivittatus (Say) (?) (p. 66) 



Pleurites in first abdominal segment less than three-fourths as long 

 as sternal plate the edwardsi group (p. 56) 



6. Urogomphi and prongs relatively short and thick (fig. 13, d, i) ; two 



pairs of lateroepicranial setae the aeripennis group (p. 41) 



Urogomphi and prongs relatively long and slender (fig. 13, /, h) ; only 

 three prominent lateroepicranial setae the inflatus group (p. 49) 



7. Ninth abdominal segment with prominent pits on dorsum (fig. 14, ;') ; 



proxistipes and dististipes distinct (fig. 14, h) 



the rotundicoUis group (p. 94) 



Ninth abdominal segment lacking prominent pits (fig. 14, i) ; proxi- 

 stipes and dististipes not distinct 8 



8. Conspicuous color pattern on dorsum; urogomphi (fig. 14, c) with 



inner prongs (ipr) large and broadly rounded at tips 



bipustulatus (Linnaeus) (p. 106) 



Without conspicuous color pattern ; inner urogomphal prongs with 



sharp tips (ipr, fig. 14, i) 9 



9. Outer prongs of urogomphi with sharp tip curving forward (opr, 



fig. 13, c) ; prongs subequal or outer prongs longer; only one 

 "sensory" appendix on second segment of antenna 10 



Outer prongs of urogomphi of different type (opr, fig. 13, g) ; prongs 

 subequal or inner prongs longer ; normally with more than one 



"sensory" appendix on second segment of antenna 11 



ID. Ninth abdominal segment (fig. 14, i) with setae (usually four) on 

 central dorsal area ; head with dorsal posteroepicranial setae (ped, 

 fig. 10, ^) ; nasale tridentate at tip the nitidulus group (p. in) 



Ninth abdominal segment without setae on central dorsal area; head 



without dorsal posteroepicranial setae ; nasale unidentate 



the propola group (p. 67) 



11. Abdominal mediotergites (fig. 14, d) with impressions (im) extending 



to mediodorsal suture on second to fifth segments ; nasale uni- 

 dentate ; larvae yellowish brown the triundulatus group (p. 75) 



Abdominal mediotergites with transverse branch of impressions ex- 

 tending about three-fourths of distance from longitudinal branch to 

 mediodorsal suture; nasale tridentate at tip; larvae brown to dark 

 brown the fallax group (p. 82) 



12. Presternum of prothorax divided into 2 or more sclerites (prst, figs. 



10, d; 13, a) 13 



Presternum of prothorax (fig. 13, b) undivided, of i large triangular 

 sclerite, sometimes rather deeply incised on lateroposterior aspects. . 15 



