CARNEGIE INSTITUTION OF WASHINGTON PUBLICATION No. 70. 



PAPERS OF THE STATION FOR EXPERIMENTAL EVOLUTION, No. 8. 



CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE MUSEUM OF 



COMPARATIVE ZOOLOGY AT HARVARD COLLEGE. 



E. L. MARK, DIRECTOR. No. 188. 



PRESS OF GIBSON BROS. 

 WASHINGTON, D. C, 



