

CARNEGIE INSTITUTION OF WASHINGTON, PUBLICATION No. 114. 



PAPERS OF THE STATION FOR EXPERIMENTAL EVOLUTION, No. 13. 



CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE MUSEUM 



OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE. 



E. L. MARK, DIRECTOR. No. 199. 



The Plimpton Press Norwood Mass. U.S.A. 



