PREFACE 



THIS volume is a corrected shorthand report 

 of the course of lectures adapted to a 

 juvenile audience given by me during the Christ- 

 mas holidays 1903-4 at the Royal Institution, 

 London. The lantern slides which I used in 

 the lectures have been converted into process 

 blocks. Many of these were photographs 

 specially prepared under my direction for the 

 lectures, and are from specimens in the Natural 

 History Museum. My desire was, as far as 

 possible, to illustrate what I said by photo- 

 graphs taken from actual specimens. Some of 

 these have come out fairly well as process- 

 blocks. For several of the sHdes and figures 

 I have to thank my friend and colleague 

 Dr. Arthur Smith Woodward, Keeper of the 

 Geological Department of the Museum, to 

 whom I am greatly indebted for kind help in 

 many ways in regard to these lectures. I have 



