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Fluke—Syrphidae of Wisconsin. 221 
Thinly pilose; abdomen with yellow bands. 
Thickly pilose, abdomen not with yellow bands. 
Third vein straight or moderately curved.. Sericomyia (p. 239) 
Third vein considerably curved. Condidea (p. 240) 
Eyes pubescent .*Pyritis 
Eyes bare .,Arctophila 
Third longitudinal vein deeply curved into 1st posterior cell... . 
Third vein only gently curved. 
Hind femora thickened . 1 . 
Hind femora slender. 
Abdomen elongate, narrowed at base, spatulate in outline 
(11) . *Salningogaster 
Abdomen oval, with yellow, interrupted bands; mesonotum with 
yellow margins; antennae elongate.C hrysotoxum (p. 223) 
Face carinate or subcarinate; hind femora with an angular pro¬ 
tuberance or spur below at outer end:. 
Face protuberant in profile. Tropidia (p. 241) 
Face concave in profile, subcarinate; spur of femora bifid. 
. *Senogaster 
Face tuberculate or arched, not keeled. 
Abdomen much narrowed at base, club-shaped.*Ceriogaster 
Abdomen not at all pedunculate or basally narrowed. 
Antennae elongate; eyes pubescent; wings colored anteriorly.. 
. *“Platynochaetus ” niger female 
Antennae not elongate. 
Third joint of antennae broad; mesonotum not vittate. 
Third joint of antennae oval: 
Males holoptic; femora with protuberance below.. 
. *Merodon 
Males dichoptic; femora not with protuberance. 
Ocelli remote from each other; mesonotum not vittate. 
. *Asemosyrphus 
Ocelli not remote; mesonotum vittate....H elophelus (p. 242) 
Thickly pilose species. Malotta (p. 245) 
Thinly pilose . 
Hind tibiae of male with an internal spur.TEUCHOcxEMis (p. 41) 
Hind tibiae without such spur (Triodonta).*Pterallastes 
Thorax with distinct yellow markings other than on the humeri; 
wasp-like flies .. 
Thorax not with distinct yellow markings of the ground color 
other than rarely on the humeri. 
Hind femora swollen and with a protuberance or spur below 
distally; face carinate or subcarinate. 
Hind femora not with such protuberance or spur. 
Face concave in profile, femoral spur bifid.*Senogaster 
Face protuberant in profile; femoral protuberance not spur-like. 
.Tropidia (p. 241) 
Abdomen narrowed basally; slender species (see 27). 
Abdomen in no wise club-shaped. 
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