THE 



CAMBRIDGE NATURAL HISTORY 



EDITED BY 



S. F. HARMER, Sc.D., F.R.S., Fellow of King's College, Cambridge ; 

 Keeper of the Department of Zoology in the British Museum 

 (Natural History) 



A. E. SHIPLEY, M.A., Fellow and Tutor of Christ's College, 

 Cambridge ; Reader in Zoology in the University 



VOLUME IV 



