ZOOLOGY 



AN ELEMENTARY TEXT-BOOK 



BY 



SIR A. E. SHIPLEY, G.C.B.E., Sc.D., 

 Hon.D.Sc. (Princeton), F.R.S. 



MASTER OF CHRIST'S COLLEGE, CAMBRIDGE 

 AND UNIVERSITY LECTURER IN ZOOLOGY 



AND 



E. W. MAcBRIDE, M.A. (Cantab.), 

 D.Sc. (Lond.), Hon.LL.D. (M c Gill), F.R.S. 



SOMETIME FELLOW OF ST JOHN'S COLLEGE, CAMBRIDGE 



PROFESSOR OF ZOOLOGY IN THE IMPERIAL COLLEGE OF SCIENCE .AND 



TECHNOLOGY, LONDON 



FOURTH EDITION 



CAMBRIDGE 

 AT THE UNIVERSITY PRESS 



1920 



