Preface 



All of the illustrations of the reptiles themselves, are photo- 

 graphic; every photograph, of this large series, is an original. 

 The illustrations were procured under the most varied con- 

 ditions, but most of them are exposures of from one to five seconds, 

 and were taken through a ray filter. With the exception of 

 six illustrations* (of turtles), all of the photographs were taken 

 by the writer. 



My camera has worked hard and faithfully and the details 

 of structure have been fully portrayed, but in a work like this, 

 colour value in the pattern is of great importance, and here the 

 camera has its limitations, though assisted by the ray filter and 

 colour-sensitive plates. A great amount of work was done 

 upon the negatives themselves, and in this, the use of restrain- 

 ing dyes formed an important part; some of the developed 

 plates were put through a half-dozen processes before they 

 passed a satisfactory test. Those illustrations of snakes that 

 are blotched or ringed with scarlet (a difficult problem for the 

 camera) are good examples of the final result. 



* For these T am indebted to Mr. Herbert Lang. 



