192 NEW YORK STATE MUSEUM 



ee Basal joints black 



/ Crossvein clouded with black or brown 

 g Fore metatarsus about V/^ times its tibia in length; ante- 

 rior tarsi of both sexes very slender and without hairs or 



with but few hairs ; legs pale 20. r i p a r i u s 



gg Fore metatarsus less than I14 times its tibia in length ; 



anterior tarsi of the male bearded 



h The second fore tarsal joint shorter than the third ; male 



fore tarsi long and densely bearded. . . .21. b a r b i p e s 



hh The second fore tarsal joint longer than the third; male 



fore tarsi long but thinly boarded. . . .22. annularis 



ff Crossvein not clouded 



g Length about 7 mm. ; black, abdomen black, in the male 

 sometimes with yellow latteral spots; male fore tarsi 

 delicately bearded ; fore metatarsus about 1^/^ times the 



length of its tibia 23. d i s p a r . 



gg Length less than G mm. 



h Thorax shining black, not striped ; abdomen black 

 i Legs blackish, fore metatarsi white ; length 4 mm. 



24. albimauus 

 it Legs pale yellow ; abdomen of female with paler base ; 



length 3.5 mm 25. tenellus 



hh Thorax duller, with indications of black or grey stripes 

 i Abdomen either olive green, or black and white 

 ;■ AVith dark olive green abdomen ; legs ferruginous ; 



length 4.5 mm. ; male 26. c h 1 o r i s 



jj With white posterior margin on each abdominal seg- 

 ment ; legs black and white ; length 4 to 5 mm. 

 Jc Fore femora black, fore metatarsus less than 1.33 



times as long as its tibia 27. devinctus 



JcJc Middle section of each femur, white ; fore meta- 

 tarsus about 1.6G times its tibia in length 



28. c a 1 i f o r n i c u s n. sp. 

 a Abdomen black 



;■ Thorax blackish with black stripes; legs wholly 

 white, except sometimes middle section of fore 

 femora is brownish (abdomen of male is white) ; 



female 32. nigricans n. sp. 



jj Thorax dark brown with broad yellowish median 

 vitta on anterior half and a pair of gray vittae on 

 posterior part ; abdomen velvet-black, hairs yellow 



(District of Ck>lumbia) 29. p a 1 11 a t u 3 



hh Thorax or abdomen or both with considerable green or yellow or gray 

 c Thorax entirely shining black, excepting sometimes the humerus, 

 which may be yellow 



d Abdomen yellow with brown bands 1. brachialis 



dd Abdomen bright green, paler when dry, posterior segments darker 

 e Halteres wholly pale 30. pedellus 



