PLECOPTERA OF NORTH AMERICA 



19 



The crossveins in the median space varied as follows : 



No. of crossveins 12 3 4 5 6 7 



Times occurring, fore wing 1 8 11 10 2 3 



These are wanting entirely in the hind wing. 



The crossveins in the cubital space varied as follows: 



No. of crossveins 123456789 10 11 



Times occurring, fore wing 2 312 10 7 1 1 



Times occurring, hind wing 122677812 



Showing a wider range of variability in the hind wing but 

 a mode at 7 in both wings. 



Extra crossveins occurred among the branches beyond 

 the cord, 89 of them in all in the 72 wings, and more often 

 several in one specimen than singly. These occurred 27 

 in males, 62 in females; 36 in fore wings, 53 in hind 

 wings; 68 in interspaces of the radial sector, and 21 

 farther rearward. 



Sc 



R. 



-Rs 



34A 



2dA 



Fig. 5. Wings of Neoperla clymene Newm. 



The branching of the radial sector is in this species 

 rather constant, though differing in the sexes. It is 4- 

 branched in the male and 5-branched in the female. But 

 3 wings out of the 72 departed from these numbers. 



The branching of the tips of vein Cu is exceedingly in- 

 constant. Though in number the tips range only from 2 to 

 5, fifteen types of branching were noted among them. But 



