94 OHIO BIOLOGICAL SURVEY 



Pterallastes Loew. 



83 P. thoracicus Loew. Eight males and one female, Hinckley, Ira, 

 Ft. Ancient, Cincinnati (Dury); June 10 to late August. 



Senogaster Macquart 



'^S. con/s^od-/ WiWst. (N. Y.) 



Syritta St. Fargeau and Serville 



84 S. pipiens Linne. Abundant; specimens from Eakeville, Colum- 

 bus, Medina, Sandusky, Wauseon; early May to early October. The 

 males have an area of enlarged facets above. One female has front all 

 black, mcstly shining; the face also dark brown. (Figs. 232, 234.) 



Xylota Meigen 



1 Legs wholly black; hind femora much thickened 2 



Legs not wholly black 3 



2 Wholly black ; wings black chalybea 



Abdomen chiefly red; the second segment with a basal black triangle; wings 



nearly hyaline pigra 



3 Second and third abdominal segments (at least) red 4 



Second and third segments wholly black, or with yellow spots 6 



4 Abdomen wholly red except the first segment; hind coxae of the male without 



a tooth below *buolor Loew (111., Pa., N. J.) 



Abdomen except the first segment, not wholly red 5 



5 Second abdominal segment with a basal black triangle; the 2-4 segments wilh 



narrow lateral black margins marginalis 



Abdomen not so marked; hind coxae of male with a spur below 



*flavitibia Bigot (Cal., Col., Nebr., D. C, N. M.) 



6 Front and middle legs and a large part of the hind femora yellow; large 



species; coxae black *cnrripes hoew (N. H., N. Y., Minn., Cal.,) 



Front legs in large part black 7 



7 Abdomen, long, slender, with two distinct yellow spots on the second 



segment • .angustiventris 



Abdomen not unusually slender 8 



8 Abdomen with two pairs of yellow spots 10 



Abdomen wholly black • 9 



9 Third joint of antennae but little longer than broad, subquadrate, reddish- 



brown; the two basal joints black ; arista luteous at the base anthreas 



Third joint large, much longer than broad elongata 



10 Hind femora much thickened, smaller species; arista yellow at the l)ase 



fraudulosa 



Hind femora moderately thickened 1 1 



