18 BULLETIN 116, UNITED STATES NATIONAL MUSEUM. 



19. Hypopygium short , with small yellowish lamellae 20. 



Hypopygium of normal size 21 . 



20. Antennae wholly black (New York) No. 98, cuniculus, new species. 



First antennal joint conspicuously yellow below (Elaine; Labrador). 



No. 97, abbreviatus. new species. 



21. Hind femora ciliated on lower inner edge 22. 



Hind femora without cilia 30. 



22. Fore tarsi ornamented 23. 



Fore tarsi plain 25. 



23. Fore coxae yellow (Alaska; Europe) No. 119, plumitarsis Fallen. 



Fore coxae black 24. 



24. Fifth joint of fore tarsi notched at tip so as to form two nearly equal lobes; first 



three joints slender, yellow (western) No. 121, obcordatus Aldrich. 



Fifth joint of fore tarsi divided into two unequal lobes, the upper one much the 

 largest; first three joints slender, first yellow, other two white, all with black 

 tips (California) No. 120, pollex Osten Sacken. 



25. Antennae wholly black; face yellowish 26. 



First antennal joint distinctly yellow below 27. 



26. Fore coxae with conspicuous black hairs on the anterior surface; third antennal 

 joint a little longer than wide, rather rounded at tip (Ontario; Newfoundland; 



Massachusetts) No. 102, melanocerus Loew. 



Fore coxae with delicate yellow hairs on anterior surface; third antennal joint 

 twice as long as wide, pointed at tip (Massachusetts; Maryland; Virginia; 

 New York; Ontario) No. 103, pantomimus Melander and Brues. 



27. Cilia of hind femora short, about three-fourths as long as width of femora (New 



York; Indiana; Ontario) No. 101, incisuralis Loew. 



Cilia of hind femora as long or longer than the width of the femora 28. 



28. Costa with a knotlike enlargement at junction of first vein; hypopygial lamellae 



about as long as wide, somewhat orbicular (Eastern States). 



No. 106, setosus Loew. 



Costa enlarged at junction of first vein, gradually tapering to its tip; lamellae 



distinctly longer than wide 29. 



29. Middle basitarsi with a large bristle above; hypopygial lamellae oval, rounded 



at tip; fore tarsi with the joints normal (Illinois). .No. 105, decorus, new species. 

 Middle basitarsi without a bristle above; lamellae subquadrate, truncate at tip; 

 second, third, and fourth joints of fore tarsi narrowed at base (Maine). 



No. 107, serratus, new species. 



30. Third antennal joint twice as long as wide (Ontario) . . No. 191, sicarius, new species. 

 Third antennal joint not over one and one-half times as long as wide 31. 



31. Fore tarsi ornamented 32. 



Fore tarsi plain 35. 



32. Fifth joint of fore taisi scarcely compressed, small (Ontario). 



No. 94, canadensis, new species. 

 Last joint of fore tarsi distinctly compressed and dilated 33. 



33. Third joint of fore tarsi half as long as first (Vancouver Island; Idaho; Washing- 



ton) No. 122, pernix Melander and Brucs. 



Third joint of fore tarsi one-fourth or less than one-fourth as long as first 34. 



34. Fourth and fifth joints forming an oval tip to the fore tarsi (Eastern States) 



No. SO, virga Coquillett. 



The oval tip to fore tarsi formed by the fifth joint only, which is equal to the 



third in length (California) No. 149, speciosus, new species. 



35. Fore coxae partly or wholly black 36. 



Fore coxae wholly yellow, or vnth a small blackish spot at base on outer sur- 

 face 38. 



