1913] North American Dipterous Genus Neiirigona 25 



I wish to acknowledge my indebtedness to those who have 

 sent me material for study, and thereby made the revision of 

 this genus possible. To Prof. J. M. Aldrich for the loan of his 

 material, and his help during the preparation of this paper; to 

 the authorities of the National Museum for the loan of spec- 

 imens, and to Mr. Knab for his help in looking up references in 

 the National Museum hbrary; to Mr. Nathan Banks, Prof. C. 

 W. Johnson, Prof. A. L. Melander, and Mr. V. A. E. Daecke, for 

 the loan of their material; and to Mr. E. T. Cresson for the loan 

 of the material of the American Entomological Society. 



TABLE OF SPECIES. 



MALES. 



1. Dorsum of the thorax mostly black, green or blue 2 



Dorsum largely yellow 17 



2. Hypopygium yellow 3 



Hypopygium black or testaceous 7 



3. Dorsum of the thorax bright blue. (West Indies) 16 decora 



Dorsum black or greenish •. 4 



4. Abdomen with black bands 5 



Abdomen marked with green 6 



5. Front tibiae with a row of bristles above, front tarsi plain 27 tibialis 



Front tibiae plain, third joint of front tarsi white, fourth and fifth joints 



black 23 tarsalis 



6. Adbomen marked with brilliant green, appendages of the hypopygium 



small. (Eastern species) 25 lateralis 



Abdomen marked with darker green, appendages long .well developed. 

 (Western species) 26 setosa 



7. Abdomen yellow with black bands 8 



Abdomen nearly uniform, color blackish 15 



8. Costa strongly arcuated. (Figs. 17 and 18) . , 9 



Costa normal 10 



9. Front tarsi with the second, third and fourth joints flattened and fringed 



with hairs 18 deformis 



Front tarsal joints not flattened, fifth black and bent at a right angle. 



17 arcuata 



10. Thorax bright shining green. 15 viridis 



Thorax if green dull 11 



1 1 . Front tarsi plain 14 



Front tarsi ornamented 12 



12. Front tarsi black, fringed on each side with short hairs 28 ciliata 



Front tarsi with an oval tip 13 



13. Front tarsi two- thirds as long as their tibiae 20 pectoralis 



Front tarsi about as long as their tibiae 19 tenuis 



14. Plurse and dorsum blackish 21 aestiva 



Plurae and sides of dorsum yellow, most of dorsum black and polished. 



5 nitida 



15. Front tarsi plain 31 albospinosa 



Front tarsi with an oval tip 16 



16. Front tibiae longer than their tarsi 29 perbrevis 



Front tibiae shorter than their tarsi 30 australis 



17. Front tarsi ornamented 18 



Front tarsi plain 19 



18. Front tarsi with an oval tip 4 carbonifer 



Front tarsi with the second joint flattened and widened at the tip, other 



joints cylindrical 12 aldrichii 



