PLATE XXIV. 



Figs, i to 7. Male of Sympetrum corruption Hagen. 



Fig. 1. Head of adult showing relative size and shape of the large and small 



facetted areas, X 8. 

 Fig. 2. Cross-section of the right eye of adult, X 34- 

 Fig. 3. A. A few elements from the small facetted deeply pigmented part of 



the eye (adult), X I 4 I - 

 B. Cross-section of a cone and its surrounding secondary pigment 



cells from A, X 500. 

 Fig. 4. A. Ommatidia from the large facetted part of the eye of 6". corrupta, 



XHi- 



B. Cross-section of three of the rhabdome-like bodies, rb of 4, A, 



X 5°°- 



C. Cross-section of the retinula in the region of the nuclei from Fig. 



4, -4, X 385- 

 Fig. 5. Head of a male nymph 5 1 . corrupta, showing the triangular large 



facetted area forming. 

 Fig. 6. Cross-section of one eye of Fig. 5. 

 Fig. 7. A. A single ommatidial element from the developing large facetted 



area of a nymph of S. corrupta, X 3^5- 

 B. Two of the upper modified hypodermal cells from the margin x 



of Fig. 6, X 3S5- 

 Figs. 8 to 11. Eye of male Bibio hirtus Goef. 

 Fig. 8. Longitudinal sagittal section of right eye, X4i« 

 Fig. 9. A. Three ommatidia from the large facetted area, X 2 °5- 



B. Cross-section of cone tip through cone nuclei and surrounding 



secondary pigment cells. 



C. Cross-section of three retinulae near their distal ends. 

 E. Cross-section of a retinula near its middle. 



D. Cross-section of three retinula; in region of retinular nuclei. 



4S0 



