78 OHIO BIOLOGICAL SURVEY 



Antennae short, the third joint not more than twice as long as wide; third vein 

 nearly straight, or gently or considerably curved into first posterior cell. ... 57 



57. Thinly pilose; abdomen with yellow bands 58 



Thickly pilose; abdomen not with yellow bands 59 



58. Third vein straight or moderately curved (Fig. 238) Sericomyia (p. 90) 



Third vein considerably curved Condidea Coq 



59. Eyes pubescent Pyritis 



Eyes bare Arctophila 



60. Third longitudinal vein deeply curved into first posterior cell 61 



Third vein only gently curved 70 



61. Hind femora thickened 63 



Hind femora slender 62 



62. Abdomen elongate, narrowed at base, spatulatein outline Salpingogaster 



Abdomen oval, with yellow, interrupted bands; mesonotum with yellow margins; 



antennae elongate (Fig. 241 ) Chrysotoxum (p. 80) 



63. Face carinate or subcarinate; hind femora with an angular protuberance or spur 



below at outer end (Fig. 233): 



Face protuberant in profile (Fig. 229) Tropidia (p. 92) 



Face concave in profile, subcarinate; spur of femora bifid Senogaster 



Face tuberculate or arched, not keeled 64 



64. Abdomen much narrowed at base, club-shaped Ceriogaster 



Abdomen not at all pedunculate or basally narrowed 65 



65. Antennae elongate; eyes pubescent; wings colored anteriorly 



' 'Platynochaetus" niger. female. 



Antennae not elongate 66 



66. Third joint of antennae broad; mesonotum not vittate 68 



Third joint of antennae oval. 



Males holoptic; femora with protuberance below Merodon 



Males dichoptic; femora not with protuberance 67 



67. Ocelli remote from each other; mesonotum not vittate Asemosyrphus 



Ocelli not remote from each other (Figs. 218, 219); mesonotum vittate Helophilus 



(P- 92) 



68. Thickly pilose species Mallota (p. 93) 



Thinly pilose 69 



69. Hind tibiae of male with an internal spur (compare Mallota sp.) 



Teuchocnemis 



Hind tibiae of male not with such spur ( Triodonta, Polydonta) 



Pterallastes (p. 94) 



70. Thorax with distinct yellow markings other then on the humeri; wasp-like flies 



81 



Thorax not with distinct yellow markings of the ground-color other then rarely 

 on the humeri 71 



71. Hind femora swollen and with a protuberance or spur below distally; face 



carinate or subcarinate 72 



Hind femora not with such protuberance or spur 73 



72. Face concave in profile; femoral spur bifid Senogaster 



Face protuberant in profile; femoral protuberance not spur-like (Fig. 233) 



Tropidia (p. 92) 



