PROCEEDINGS 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. VIII, pp. 459-486. pls. xxiv-xxviii March 6, 1907. 



HISTOLOGY AND DEVELOPMENT OF THE DIVIDED 

 EYES OF CERTAIN INSECTS. 



By George Daniel Shafer. 



Exner, 1891, Zimmer, 1897, and Kellogg, 1898, 1900, and 

 1903, have discussed the divided-eye condition of certain crus- 

 taceans and insects. It is the purpose of the following paper: 



1. To describe the histological structure of the divided com- 

 pound eyes of Sympetriim corrupta, Anax Junius, Dibio hirtus, 

 two species of Blepharoceridaj and two species of CaHibcetis. 



2. To describe the development of the large-facetted area of 

 the eye in CaHibcetis and Sympctrum corrupta. 



3. To refer briefly to the significance of the divided-eye con- 

 dition in these eyes. 



This investigation was made in the Entomological Laboratory 

 of Stanford University, under the direction of Prof. V. L. 

 Kellogg. I wish here to thank Professor Kellogg, Mr. Doan 

 and Miss McCracken for help in the laboratory ; also Professor 

 Aldrich, Dr. Needham and Mr. Grinnell for identifying some 

 of the material used. 



SYMPETRUM CORRUPTA Hagen. 



The compound eyes of Sympctrum corrupta, as shown in 

 Fig. 1, Plate XXIV, are divided by a curved line into almost 

 equal upper and lower parts. The lower half of the eye is 

 dark and a good hand lens shows it to be made up of very 

 small facets. The upper half is lighter in color and made up 



Proc. Wash. Acad. Sci., March, 1907. 459 



