VI PREFACE, 



characteristics have been added, and it is hoped that 

 this will enable readers to identify any such species of 

 Heliozoa which they may meet with. For further 

 information Penard's work may most conveniently be 

 consulted. 



The sudden death of Mr. John Hopkinson in July, 

 1919, deprived me of his valuable assistance and has 

 necessitated the omission of the complete biblio- 

 graphy of the Heliozoa which he had in preparation. 

 The more important references, however, are given in 

 the synonymy of each of the species. Mr. Hopkinson 

 had revised the manuscript and arranged the plates 

 and text-figures. He also re-drew several figures 

 from the publications of previous authors. 



Dr. Caiman kindly undertook to see the volume 

 through the press and to read "the proofs. He has 

 also verified all the bibliographical references and 

 compiled the index. My thanks are due to him for 

 his kind co-operation. 



G. H. WAILBS. 



CoETES Island, B.C., 



Canada ; 



October, 1920. 



