Foreword 



Captain Young and I for some years 

 have been gathering material from all 

 over the world about the Selachians— the Sharks, Skates, Rays, and their 

 allies— of which there are more than 600 known species. We originally 

 intended merely to up-date Captain Young's book ''Shark!! Shark!!'''' 

 (published by Gotham House in 1934, and now a collector's item), but, 

 as the material ever expanded, it was decided that an entirely new book, 

 covering a much broader field, was needed. 



Adaterial was collected from all over the world for many years. When 

 Captain Young and I felt that the research was nearly completed, we 

 called upon Tom Allen, an experienced newspaperman, to aid us in trans- 

 forming the research material into a book. Tom and I continued the 

 research up to (and beyond!) the completion of the manuscript. Tom 

 also did further research and added new material in the course of writing 

 the book. 



In all scientific classifications, the Selachians are separated clearly 

 from the Teleosteans, or Bony Fishes, and there are even leading ichthyol- 

 ogists \\ ho do not regard the former as fishes at all but rather as repre- 

 senting a separate and distinct Class of animal life. 



Selachians are among the most adaptable and hardy forms of life on 

 this planet and have survived longer hereupon than most. Among them 

 are probably the most deliberately ferocious forms of life on earth. The 

 Selachians are to be found from polar to equatorial seas; from shallow 

 to abyssal waters; in salt, brackish, and fresh waters; and all over the 

 world. Some have changed little, if at all, during millions of years. No 

 one knows just how many kinds exist today, and scientific expeditions 

 probing both the ocean depths and tropical jungle rivers continue to find 

 new ones almost every year. 



The behavior of sharks toward men is inexplicable and may possibly 

 forever be a mystery. The more that they are observed, the less certain 

 we seem to be as to just what motivates them. Even those considered 

 most dangerous are known to have ignored men who were helpless in 

 the water beside them. Other species, long considered to be harmless, 

 have been reported to have attacked swimmers and divers without 

 provocation. The United States of America and several other Govern- 



