227 



7. Green species ; abdomen Avith a transverse pair of black spots on 



segments 3 and 5 ; all tarsal claws single, with a short basal tooth 

 viridis Coquillett. 



— Yellow species 8 



8. Tarsal claws small ; last tarsal joint without ventral spines 



gilva Coquillett. 



— Tarsal claws large; last tarsal joint with si)ines on the ventral 



surface flavidula, n. sp. 



9. Last tarsal joint without any spines on the ventral surface 10 



— Last tarsal joint with at least a pair of spines on the ventral surface 



12 



10. Fore and mid tarsi with the claws equal, the posterior pair single, 



with a basal tooth polita Coquillett. 



— Claws on all tarsi subequal 11 



11. Small s])ecics, 1 mm.; claws minute; vein 3 united to vein 1 on its 



basal fourth arctica Coquillett. 



— Larger species, 4 mm. ; claws rather large ; vein 3 united to vein 1 



by the normal cross vein magna Coquillett. 



12. All tarsal claws single, with a basal tooth 13 



— At least the anterior pair of tarsi with the claws subequal 14 



13. Abdomen black antennalis Coquillett. 



— Abdomen green diver sa Coquillett. 



14. Fourth vein with the lower branch obliterated except towards its 



apex stigmalis Coquillett. 



— Fourth vein forking a short distance before the cross vein; both 



branches complete caudelli Coquillett. 



The males of but few of the species in this genus and its allies are 

 known, and it is not necessary to include in this table the only male 

 I know. It will be necessary to have separate tables for determining 

 the sexes, as the males will often, probably always, present characters 

 differing from those of the females. 



JOHANNSENlELIvA BIMACULATA LoCW 

 Ceratopogon bimaculatiis Loew, Dipt. Amer. Sept. Indig. Cent. 1, 1861, sp. 6. 



Female. — Glossy black, without distinct pollinosity. Head black 

 or brown-black ; scape of antenna yellow, flagellum black ; face 

 brownish yellow ; proboscis and palpi yellow. Pleurae brown-black, 

 becoming yellow on the lower portions. (I can not see the white 

 vitta mentioned by Loew in any of the s]iecimens before me.) 

 Abdomen brownish on the venter. Legs, including the coxa;, yellow; 

 hind femora with a brown ring on apical fourth, apices of tibiae 

 slightly l)r()wned, apices of first three tarsal joints indistinctly 



