146 KANSAS UNIVERSITY SCIENCE BULLETIN. 



frequency of certain group types in the male and the female 

 was not found. The polygonal gi'oups are oftener without the 

 central disk dark than with. When this was not pigmented, 

 the space was still clouded the same as the cuticula surround- 

 ing the pigmented disks. 



I 



tt 



^ 



^. A 



^ :• 'i 



^ :: •' 



• 



Fig. 61. — Diagram showing principal forms of 

 groups found in the pattern. 



The disks were found to be smaller proximad of the base of 

 the wing and near the veins and the anal fold, and consequently 

 the groups there were either of uniformly small disks or of part 

 normal and part small-sized disks. There were no groups on 

 the stigma ; here the disks became reduced to mere low, conical 

 projections. The anal fold was smooth and transparent, with 

 clear-cut edges. 



Cross section (30-9, c) shows on the lower side of the wing, 

 !»pposite each disk, a small, blunt outgrowth, generally unpig- 

 mented. 



Hind Wing, — Here the disk structure of the membrane is 

 barely visible under favorable conditions of illumination of the 

 microscope. Only those disks on the clavus are pigmented. 



