vi PREFACE 



Protozoology^ Hegner and Taliaferro, Textbook of Comparative 

 Anatomy, Lang, Textbook of Zoology , Parker and Haswell); Messrs 

 Methuen & Co., Ltd. (Textbook of Entomology , Imms); Oxford Uni- 

 versity Press {The Animal and its Environment and Manual of Zoology, 

 Borradaile). Acknowledgment to the authors of the works from which 

 these illustrations are taken is made in the legends. 



THE AUTHORS 



CAMBRIDGE 



February, 1932 



NOTE TO THE SECOND EDITION 



The book is now eighty pages longer. The additional matter is chiefly 

 in Chapters IV and XIV. In other chapters a number of smaller 

 additions and corrections have been made to the text and to figures. 



Each chapter has been revised by its writer, but the revision has 

 been submitted to the other authors of the book. 



Our grateful thanks for various assistance are due to Drs A. M. 

 Bidder, O. M. B. Bulman, S. M. Manton, and C. F. A. Pantin, and 

 to Messrs L. E. R. Picken, J. D. Robertson, and P. Ullyott. Dr A.M. 

 Bidder very kindly communicated to us certain facts, as yet unpub- 

 lished, which are stated in the second half of p. 595. 



THE AUTHORS 



CAMBRIDGE 



February, 1935 



