THE 



CAMBRIDGE NATURAL HISTORY 



EDITED BY 



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

 Superintendent of the University Museum of Zoology 



A. E. SHIPLEY, M.A., Fellow of Christ's College, Cambridge; 

 University Lecturer on the Morphology of Invertebrates 



VOLUME VI 



