144 Annals Entomological Society of America [Vol. II, 



34. Gray of the wings in the form of spots in the cells at the apex and 

 along the posterior border, leaving the veins margined with 

 hyaline tenebrosus Will. 



Apex and posterior border of the wing uniformly gray. In some 

 species this coloring is very feint 35. 



.35. Ventrally the posterior margin of the eighth abdominal segment of 



the male is somewhat produced avidus v. d. Wulp. 



Ventrally the posterior margin of the eighth abdominal segment is 

 not produced 36. 



36. Black species 37. 



Gray, brown or yellowish brown species 40. 



37. Small species, legs black, at most with just a trace of reddish on the 



base of each tibia maneei n. sp. 



Larger species. Legs plainly marked with red 38. 



38. Male upper forceps long, usually longer than the last three abdominal 



segments together. Mystax largely black sadytes Walker 



Male upper forceps shorter, usually about as long as the first two 

 abdominal segments together. Mystax largely light 39. 



39. Eastern species. Each tibia red on basal third notatus Wied. 



Western species. Each tibia largely red, especially on the posterior 



side callidus Will. 



40. Rather large species, wings wide, end lamellae of the ovi])ositor 



wedged in lecythus Walker 



End lamellae of the ovipositor not wedged in 41. 



41. All the femora wholly black novae-scotiae Macquart 



Femora partly red, at least each with a preapical red band 42. 



42. Feinora variable, sometimes wholly red, commonly with only the 



posterior side red, mystax almost always white or yellowish white . 43. 



Femora largely black, mystax in large part black, from side view 



male genitalia widest at two thirds the length erythocnemius n. sp. 



43. Small reddish species, mystax straw yellow, legs mostly red, male 



genitalia red rubidus n. sp. 



Larger species, mystax white, occasionally a few black bristles above, 



male genitalia black antimachus Walker. 



44. Small reddish species, legs red, at most only the anterior side of each 



femur slightly darkened, male genitalia red rubicundus n. sp. 



Femora in large part black. Species of ordinary size 45. 



45. Each femur with a preapical band and the posterior side red 46. 



Each femur with only a preapical band red 48. 



46. Dull gray species, under side of each front femtu- with numerous 



gray hairs delusus Tucker 



Bright gray or yellowish species, under side of each front femur with 

 a longitudinal row of bristles 47. 



47. Thorax with a very distinct mid-dorsal black stripe which reaches its 



entire length, male genitalia dark red johnsoni n. sp. 



Mid-dorsal thoracic stripe not very distinct and abbreviated behind. 



JVIale genitalia black, or at least dark fuscus prairiensis Tucker. 



48. Under side of each front femiu- furnished with abundance of rather 



lon'g hairs, not in rows snowii n. naine. 



Under side of each front femur with a row of bristles 49. 



49. Bristles on the under side of each front femur white and rather weak. 



Upper forceps of male genitalia from side view widest at two thirds 



the length erythocnemius n. sj). 



Bristles on the under side of each front femur rather stout, nearly 

 always partly or wholly black, upper forceps of the male genitalia 

 from side view of the same width throughout paropus Walker 



