ABT. 17. FLIES OF THE GENUS TACHYTRECHUS GREENE. 3 



10. Femora entirely yellow 11. 



Femora black or yellow with blackish Infuscations 14. 



11. Fi-ont femora with long crinkly or straight hairs 12. 



Front femora without long hairs 13. 



12. Front femora with long crinkly hairs on the outside surface. 



No. 11. auratus Alclrich. 

 Front femora with long straight hair on the under side. 



No. 7. bipunctatus, new species. 



13. Femora and tibiae entirely yellow; middle tibae with three or four large 



macrochaetae on the apical half of the inner flexor side; also a row of 

 large bristly hairs the entire length of the outer flexor side. 



No. 8. tenuiseta, new species. 



All femora yellow; hind tibiae yellow with a blackish infuscation at the 



tip ; arista slightly longer than height of head, lamella large and rounded. 



No. 12. moechus Loew. 



14. Front femora yellow, very much enlarged on basal half; with a large 



brownish-black spot on the outside No. 10. olympiae Aldrich. 



Front femora normal 15. 



15. Front femora yellow ; middle and hind femora faintly blackish at the base ; 



middle tibiae with one large macrochaeta on inner flexor side near the 



apex No. 13. sanus Osten Sacken. 



All femora greenish black; front tibae pale yellow; extremely broad on 

 apical two-thirds ; with a row of black, flat bristles on flexor side. 



No. 9. laticrus Van Duzee. 



Key to the Females. 



1. Wing with an apical cloud No. 1. simulatus, new species. 



Wing without any cloud 2. 



2. Antennae entirely black 3. 



Antennae black and yellow . 7. 



3. Legs black 4. 



Legs mostly gray or yellow 5. 



4. Front tibiae with four extremely long macrochaetae on outer flexor side ; 



hind femora with a bronze reflection No. 2. rotundipennis, new species. 



Front tibiae with two small macrochaetae on outer flexor side ; hind femora 

 with a green reflection No. 15. angustipennis Loew. 



5. Legs with red or yellow markings 6. 



Legs without any red markings No. 4. floridensis Aldrich. 



6. Legs mostly pale yellow with only small blackish Infuscations. 



No. 5. volitans Melander. 

 Legs mostly reddish-yellow 7. 



7. Hind femora black with silver and green reflections; apical third reddish- 



yellow ; hind tibiae reddish-yellow with apex blackish. Species with a 

 bright green or red reflection ( western )_No. 11. granditarsus, new species. 



Hind femora the same as above with only the apices reddish-yellow; 

 bronze species No. 3. vorax Loew. 



Characters not as above 8. 



8. First antennal joint entirely yellow 9. 



First antennal joint infuscated above 10. 



9. Femora entirely yellow No. 11. auratus Aldrich. 



Femora entirely black No. 9. laticrus Van Duzee. 



Femora black with apical third yellow No. 13. sanus. Osten. SiKken. 



