AMERICAN DIPTERA. 273 



Pelastoneurus is wide and bulges below, while in Sarcionus it is nar- 

 row and does not bulge. 



To avoid mistakes of generic reference, I have combined the 

 tables of the three genera. 



Combination Table of North American Species. 



1. Femora largely black 2. 



Femora yellow, or but little infuscated 10. 



2. First part of costa greatly thickened in the male, noticeably so in the 



female 3. 



First part of costa not perceptibly thickened 4. 



3. Tibiae yellow (W. I.) ParacliuM abtloininalis Aldrich. 



Tibite black (La., N. Y., Cuba, Mex.). . Pariiclius albonotatiis Loew. 



4. Fore femora yellow, middle and hind ones with the apical third and half 



respectively black (Mex.) Paracliiis f*eiu<»ratiis Aldrich. 



Fore femora black, with yellow tips; middle black, with apical half yellow; 



hind ones yellow, witii black tips (Gal.). 



Pela!«loiieuriis «lissiiiiilipe»« Wheeler. 

 Femora, at least of male, more uniformly black 5. 



5. Antennffi reddish, except the upper edge and tip; thoracic dorsum bright 



bluish green (W. I.) Paracliuiii fii!«cieoriii!!« Aldrich. 



Antennge black 6. 



6. Tibiae of male wholly black • • • 7. 



Tibiae of male largely yellow 8. 



7. Upper half of the face bright green (Mex.). 



Pelastoneurus hainatus Aid. 

 Upper half of face with whitish dust (W. I. )■ .Paracliiis nigripes Aid. 



8. Hypopygium small, rounded (Mex.) I'araclius hunieralis Aid. 



Hypopygium decidedly elongated 9. 



9. Face of male very narrow below (Tex.). • • -Paraclius puinilio Loew. 

 Face of male of uniform width (Fla.) Paraclius scutaliis n. sp. 



10. Wing of male with a rounded apical brown spot (Mex.). 



Pelastuueiirus bigemiuatus Aldrich. 



Wing in both sexes with several distinct brown spots 11. 



Wing not spotted, or with one or two spots on the veins 12. 



IL Fourth vein uniformly approaching the third (Mex.). 



Pelastoneurus puuelipeuuis Say. 

 Fourth vein bent abruptly towards the third (Fla.i. 



Pelastoneurus pictipenuis Wheeler. 



12. A spot of white pollen on the posterior part of the thorax before the scntel- 



luni (N. Y., Cal., Fla.). .. .Pelastoneurus longicauda Loew. 

 Without such spot 13. 



13. Antennal arista of male ending in a lamella 14. 



Antennal arista not ending in a lamella • • • 15. 



14. Arista of male long, tapering, thin ( W. I.). 



Paraclius discifer Aldrich. 

 Arista quite short, thick ( E. U. S) . . • • Paraciius claviculatus Loew. 



TRANS. AM. KNT. SOC. XXX. (35) SEPTEMBER. 1904. 



