940 Charles Paul Alexander 



b. The umbrosa subgroup. — Large species; the eighth stenite provided with conspicuous 

 lateral lobes, and the caudal area between with two chitinized points. 



T. umbrosa Loew 

 T. flavoumbrosa Alex. 



c. The australis subgroup.^ Medium-sized species; the lateral lobes of the eighth sternite 

 (T. australis) tending to disappear {T. dietziana) and pass into the fourth subgroup. 



T. australis Doane 

 T. dietziana Alex. 



d. The submaculata subgroup. — A great assemblage of forms, including the majority of 

 the subunicolores. Wing practically unicolorous ("except in T. huron) but the obliterative 

 streak well marked; ninth tergite variously notched medially; eighth sternite provided 

 with tufts of short to long hairs, in the specialized forms {T. tuscarora) passing into a 

 single powerful bristle on either side. 



T. mainensis Alex. 



T. mingwe Alex. 



T. georgiana Alex. 



T. monticola Alex. 



T. translucida Doane 



T. cincticornis Doane 



T. penicillata Alex. , 



T. triton Alex. 



T. submaculata Loew 



T. tuscarora Alex. 



T. huron Alex. 



5. The besselsi group. — A small group of high arctic species; coloration blue-gray; head, 

 thorax, and coxae with abundant long white hair; valves of the ovipositor suddenly narrowed, 

 weak. 



T. besselsi 0. S. 

 T. piliceps Alex. 



6. The aperta group. — A reduced species, with the venation in process of atrophy, the 

 medial cross-vein lacking. 



T. aperta Alex. 



7. The apicalis group. — An isolated species that has probably come from the valida group; 

 wing broadly tipped with brown; ninth tergite deeply notched medially. This species is 

 possibly closer to T. mainensis than this grouping would indicate. 



T. apicalis Loew 



8. The hermannia group. — Wings sparsely blotched with darker; ninth tergite with 

 a prominent, compressed, median lobe; antennae of the male elongate; not dimorphic. 



T. hermannia Alex. 



9. The anmdicornis group. — Dimorphic, the males light-colored, the females dark brown, 

 the wings practically unicolorous; male antennae elongate to very elongate (T. taughannock) ; 

 ninth tergite with a conspicuous median lobe and more or less prominent lateral lobes. 



T. annulicornis Say 

 T. taughannock Alex. 



10. The fuliginosa group. — Dimorphic, the males light-colored (T. speciosa), the females 

 very dark brown {T. fuliginosa) with white markings; ninth tergite asymmetrical, the 

 right pleurite produced caudad in a prominent two-cleft arm; ninth tergite deeply notched 

 medially. 



T. fuliginosa (Say) 



11. The trivittata group. — Wings conspicuously cross-banded, an uninterrupted white 

 band beyond the cord; ninth tergite notched, with a small tooth at the base of the 

 notch. 



T. trivittata Say 



T. angulata Loew 



T. entomophthorae Alex. 



