AMERICAN DIPTERA. 271 



31. Wings elongate, the posterior cross-vein beyond tlie middle, les.s than its 



length from tip of fifth vein (Hydrophorinte) 32. 



Wings not elongate, posterior cross-vein scarcely beyond the middle, more 

 tlian its lengtli from end of fifth vein (if less, the liind metatarsus 

 sliorter tlian the following joint 34. 



32. Fore femora slender l<iancaliis J^oew. 



Fore femora thickened, with spines below 33. 



33. Spines of fore femora very short, thoracic dorsnni without well-marked jiol- 



liuose lines HydroplioriiN Fallen. 



Spines of fore femora long, dorsum with poUinose lines. . .Scellus Loew. 



34. Outer appendages of the hypopygium filiform; arista dorsal. 



IVeinatoproctus Loew. 

 Not with both characters 35. 



35. Second joint of antenna with a thumb-like projection along the inner side 



of the third 36. 



Not with such projection 37. 



36. Face of female wide, the lower part i>rojecting, roof-like. 



JKyiitoriiioii Loew. 

 Face of female not so constructed Parasy ntoriiion Wheeler. 



37. Eyes of male contiguous or nearly so lielow the antenna; 38. 



Eyes of male contiguous or nearly so above the autennse. 



Diaplioriis Meig., pt. 

 Eyes closest together Ht the level of the antenna-; middle legs of male dis- 

 torted or with peculiai- structure C'aiiipsiciieiiiiis Walker. 



Eyes of male not contiguous nor closely approximated 39. 



38. Pulvilli of male fore tarsi conspicuously enlarged . . . f^utariiiiis Loev\. 

 Pulvilli not enlarged C'liryNotux Meigen, pt. 



39. Tiiorax bright green, abdomen yellow, with a good deal of silvery pollen. 



L.eueoNtola Loew. 

 Not so marked 40. 



40. Face broad, the palpi large, reposing on the proboscis; pollinose species. 



Thiiiophilii»» Wall 1 berg. 



Palpi of ordinary size or else projecting lamelliform, free from the pio- 



boscis 41 . 



41. Third joint of the antenna in the male conspicuously long, awl-shaped, not 



much wider at base than the first joint - . ■ Rliaplliuill Meigen. 

 Third joint long, lancet-shaped, wider than first joint. 



Porpliyrops Meig. 

 Third join short, the tip sometimes drawn out into a point 42. 



42. Abdomen of male with four blunt bristles at the tip. 



Diapliortis Meig. 

 Abdomen destitute of these bristles 43. 



43. Arista nearly or quite apical C'lirysotiis Meigen. pt. 



Arista dorsal 44. 



44. Costa thickened near the apex of the first vein ; iiind cross-vein at right an- 



gles to the costa Teuclioplioriis Loew 



Costa not tiiickened ; cross-vein slanting moie or less towards the tiji of the 

 wing .- .45. 



TRANS. AM. KNT. SOC. XXX. SKPTKMBKR. 1904. 



