THE CANADIAN ENTOMOLOGIST. 22.4 



of this family are known to extend across the continent (I have examined 

 specimens of Thereva comata from California and New Hampshire, 

 Psilocephala haemorrhoidalis from New Jersey to Arizona), there is strong 

 reason for believing that this is the true Thereva nigra of Say. For the 

 species that has hitherto borne Say's name in collections, I have adopted 

 Macquart's name of haemorrhoidalis (described under Thereva), since it 

 is very probable that this author had specimens of the present species 

 before him when drawing up the description to which the above name is 

 attached. 



Psilocephala melampodia, platancala, variegata and levigata are un- 

 known to me except from the descriptions ; of the remaining species I 

 have seen only males of melanoprocta and notata, and only females of 

 rufiventris and scutellaris. 



The table of species is as follows : — 



i. Fourth posterior cell open ; front wholly opaque and covered with 



pollen , 2 



Fourth posterior cell closed and usually petiolate 10 



2. Femora black, or blackish-brown 3 



Femora and knob of halteres yellow X .. ' * ^' 



J ( montivaga, n. sp. 



3. Wings destitute of blackish spots, except sometimes on the cross- 



veins 4 



Wings marked with over a dozen blackish spots, many of which are 

 not situated on the cross-veins ; abdomen wholly opaque ; anten- 

 nal style nearly half as long as the third joint tergissa, Say. 



4. Knob of halteres blackish-brown 5 



Knob of halteres. and hypopygium of male, yellow ; first and third 



antennal joints subequal in length, the style nearly half as long 

 as the third joint morata, n. sp. 



5. Thorax marked with light and dark coloured vittae 6 



Thorax not vittate 8 



6. Tibiae yellow 7 



Tibiae black, abdomen of female largely shining. melampodia, Loew. 



7. First joint of antennae much longer than the third, and extremely 



robust ; California species crassicornis, Will. 



First joint of antennae much shorter than the third and not 

 unusually robust ; Florida species f estiva, n. sp. 



8. Tibiae black, cross-veins of the wings not bordered with brown ; 



