HELEOMYZID FLIES NORTH OF MEXICO—GILL 501 
1 2 3 4 5 
Sere ee 
6 7 8 9 10 
Dy, v \\ 
ii 12 13 14 15 
16 17 18 19 
<= 
20 2} 22 23 24 
(For explanation see opposite page.) 
