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) 
AND 
A. BE. SHIPLEY, M.A., Fellow and Tutor of Christ’s College, 
Cambridge ; Reader in Zoology in the University 
VOLUME IV 
