142 



NORTH AMERICAN DIPTKRA. 



clows, etc. They are all rather sluggish in flight, and 

 the males are conspicuous because of the very large and 

 hairy eyes. Some of the species of Scatopse are very 

 minute, among the smallest of all diptera. But very lit- 

 tle has been done in the way of critical study of the gen- 

 era and species of this family; it is an excellent field for 

 research. 



l 3 



'""'' "" ' 



7 



Fig. 42. Bibionidae. i, Plecia, wing; 2, 3, Plecia, antennae; 4, 

 Bibio, wing; 5, Bibio, palpus; 6, Bibio, antennae; 7, Scatopse, wing; 

 8, AspisteS) wing (Wmp); 7, bis, Scatopse, wing; 7a, Scatopse, last 

 tarsal joint with claws and empodium ; 8, bis, Scatopse, wing; Sa, 

 Scatopse, head. 



TABLE OF GENERA. 



1. Second basal cell present 



Second basal cell wanting (Scatopsintr} . . 



2. Third longitudinal vein furcate. 

 Third vein not furcate. 



2 



7 



3 

 5 



3. Palpi four-jointed; antennae slender, more than ten-jointed; slen- 

 der species (Pachyneurince} 4 



Palpi five-jointed; antennae eight or nine-jointed; less slender spe- 

 cies (1, 2, 3) Plecia, 



