AMERICAN I>rPTERA. 271 



31. Wings elonorate. the posterior cross-vein beyond the middle, less than its 



length from tip of fifth vein (Hydrophorina) 32. 



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

 than its lengtli from end of fiftli vein (if less, the hind metatarsus 

 shorter than the following joint 34. 



32. Fore femora slender Liaiicaliis Loevs'. 



Fore femora thickened, with spines below 33. 



33. Spines of fore femora very short, thoracic dorsum without well-maiked )iol- 



linose lines Hytlro|»li«riiN Fallen. 



Spines of fore femora long, dorsnm with pollinose lines- • -Scellus Loew. 



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



IVeinatoproetus 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 projecting, roof-like. 



Nyiiloriiioii Loew. 

 Face of female not so constructed ParasyiltOi'iiiOll Wheeler. 



37. Eyes of male contiguous or nearly so below the antenna- 38. 



Eyes of male contiguous or nearly so above the antenna". 



Diaplioriis Meig., pt. 

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

 torted or with peculiar structure Canipsiciieillli!^ Walker. 



Eyes of male not contiguous nor closely approximated 39. 



38. Pulvilli of male fore tarsi conspicuously enlarged.. . 'Kiitarsiis Loew. 

 Pulvilli not enlarged Chrysolu^i Meigen, pt. 



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



LieuCOKtola Loew. 

 Not so marked 40. 



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



TltiuopIiiliiM Wahlberg. 

 Palpi of ordinary size or ekse jirojecting lamelliform, free from the pro- 

 boscis 41 



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



much wider at base than the first joint ••• Rliaphiiiiii Meigen. 

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



I'orphyrops Meig. 

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



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



Diaphoriis Meig. 

 Abdomen destitute of these bristles 43. 



43. Arista nearly or quite apical CIiry!<»otilS Meigeu, pt. 



Arista dorsal 44. 



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



gles to the costa Teucliophoruii« Loew. 



Costa not thickened ; cross-vein slanting more or less towards the tip of the 

 wing 45. 



TRANS. AM. ENT. SOC. XXX. .SKPTKMBKK. 1904. 



