32 OHIO STATE ACADEMY OP SCIENCE. 



CHRYSOPS Meigen. 



Illiger's Magazine II, 367, 1803. 

 The males and females in this genus are so different that it is 

 often desirable to make observations in the field before associat- 

 ing the two sexes of a species. We have made a special effort 

 to collect the sexes of our local species and have formulated sep- 

 arate keys for each sex. These keys are given below. 



Key to the Females. 



1. Apex of the wing beyond the cross-band is hyaHne 2. 

 Apical-spot present 4. 



2. Both basal cells infuscated on their basal half 3. 

 Second basal cell hyaline ; face yellow in the middle niger. 



3. Each side of the thorax with bright yellow hairs celer. 

 Each side of the thorax with pale hairs carbonarius. 



4. Whole body brown 5. 

 Abdomen marked with pure black 6. 



5. Basal segment of antenna swollen ; abdomen above brown 



with small yellow triangles on the segments brunneus. 



Basal segment of antenna not swollen ; abdomen above with 



darker designs • Havidus. 



6. Both basal cells hyaline ' 7. 

 First basal cell altogether or to a considerable extent infus- 

 cated 13. 



7. Apical-spot not wider than the distance between the costa and 



second vein at the outer border of the cross-band 8. 



Apical-spot wider than the distance between the costa and 



second vein at the outer border of the cross-band 9. 



8. A black triangle encroaches upon the posterior part of the 



yellow on each side of the second abdominal segment tnoerens. 

 No black triangle on each side of the second segment of the 



abdomen callidus. 



9. The hyaline triangle is produced beyond the second longi- 



tudinal vein toward the costa 10. 



The hyaline triangle does not cross the second longitudinal 



vein 12. 



10. Abdomen black with a middorsal stripe attenuated posteriorly 



and sometimes a shorter stripe on each side obsoletus. 



Abdomen yellow with two converging black spots on the 



second segment and black spots on the third and fourth 11. 



11. The cross-band reaches the posterior margin fallax. 

 The cross-band does not reach the posterior margin hilaris. 



12. Apical-spot occupying only the apex of the second sub- 



marginal cell sackeni. 



Apical-spot occupying the anterior half of the second submar- 



ginal cell montanus. 



