SYRPHIDJ5. 89 



0(5. Hind tibiae of the male with an internal median spur. (See alsoMallofa 



sp.) TEUCHOCNEMIS Osten Sacken. 



Hind tibiae of $ not with such a spur. POLYDONTOMYIA Williston. 



67. Hind femora thickened and with a bifid spur below (?North America). 



SENOGASTER Mac-quart. 

 Hind femora without such spur. . .*.'..-.. 68 



68. Slender species; abdomen narrowed basally. (See 28.) 



Abdomen in no wise club-shaped. . V . . . . 69 



69. Thorax with distinct yellow markings other than on the humeri. 78 

 Thorax not with distinct yellow markings of the ground color other 



than rarely on the humeri. ....... 70 



70. Face transversely arched or carinate, not produced, not tuberculate; 



abdomen more or less elongate and nearly bare. . . . 71 

 More or less thickly pilose species, often large 73 



71. Hind femora extraordinarily thickened; anterior cross-vein rectangu- 



lar. . . . . SYRITTA St. Farg. and Serville. 



Hind femora more or less thickened ; cross-vein oblique. . . 72 



72. Face sharply carinate. TROPIDIA Meigen. 



Face transversely arched. ..... XYLOTA Meigen. 



73. Scutellum, margin of the thorax and pleurae with bristly hairs. 



CHRYSOCHLAMYS Rondani. 

 Thorax wholly without bristles 74 



74. Face short, not produced, concave from antennas to tip, not tuberculate ; 



hind femora thickened. . . - t . . . . 75 



Face produced, long. ......... 76 



75. Abdomon elongate. . . ... BRACHYPALPUS Macquart. 



Abdomen very broad ; thorax densely pilose ; middle femora of the $ 



with an inferior basal spur. . . . HADROMYIA Williston. 



76. Face produced forward, pointed, concave from antennae to tip, not 



tuberculate; hind femora thickened. CRIOPKORA Osten Sacken. 



Face not evenly concave, but tuberculate or convex. ... 77 



77. Third joint of the antennae produced above into a conical process, ter- 



minating in the thickened arista. . . MERAPIOIDITS Bigot. 

 Third joint of the antennae obliquely oval ; hind femora rarely thick- 

 ened. ........ CRIORHINA Macquart. 



78. Hind femora with a conical, tooth-like protuberance below near the 



distal end. . . .'"... . . SPILOMYIA Meigen. 



Hind femora without such protuberance. . . . . . 79 



11 



