NORTH AMERICAN DIPTERA. 



acter; which I leave for Mr. Czerny to decide. His 

 genus Hendelia he distinguishes from Heteroneura by the 

 absence of the post-vertical bristles, and the more remote 

 insertion of the antennae from each other. Mr. Coquillett 

 has added another, based chiefly on the absence of both 

 postvertical and cruciate bristles. Still another from 

 South America (fig. 6) differs in the arrangement of 

 these bristles. Possibly such a division of the species 

 is natural, but I am yet to be convinced that it is. I 

 omit the preapical bristle character in the table, since 

 that, at least, seems worthless, as was observed long ago 

 by L,oew. 



TABLE OF GENERA. 



1. Cross veins approximated, the penultimate section of the fourth 



vein not more than one fourth the length of the ultimate sec- 

 tion. ........... 2 



Cross veins not approximated; the penultimate section of the fourth 

 vein at least one-third the length of the ultimate section (7 and 



p. 80, 16.) Clusia. 







2. Postvertical, ocellar and cruciate bristles distinpt (Clusiodes Coq.) 



(1, 2) Heteroneura. 



Post-vertical and ocellar bristles present, the cruciate absent (3) . 



Heteringomyia. 



Postvertical and cruciate bristles absent, the ocellar obsolescent; 

 distal end of first vein bristly (4, 5) . . . Chsetoclusia. 



For Peratoch&tus ornatus, see Geomyzidae (Spi/ochroa.} 



