VI PREFACE. 



11. Finally it must be noted 



that all the figures for PUtes I to IX, XI to XIII and XX in- 

 elusive, with the only exception of the diagrams included in 

 Plates II and IX have been drawn from nature by my wife, to 

 whose work therefore this book owes much of any interest or 

 value it may possess. 



R. 8. HOLE. 

 April 1908. 



