jv editor's preface. 



degree of indebtedness that I and previous Editors and 

 Authors owe to them, for the very great care that they have 

 throughout taken m the printing of these numerous volumes 

 and for the manner in which the standard of work has been 

 mamtained for over sixty years. 



R. B. 8EYM0UR SEWELL, 

 C.I.E., 8c.D., F.R.8., 



Lieut.-Col. l.M.S. {retd.), 

 Editor. 

 The Zoological Laboratory, 



Cambridge. 

 May, 1949. 



