XU PREFACE TO THE FIRST EDITION. 
FitzRoy, for having permitted me to volunteer my 
services on board H.M.S. Beagle, and for his uniform 
kindness in giving me assistance in my researches, I 
can here only repeat my obligations to him. The 
materials for this volume were nearly ready two years 
ago ; but owing to ill health, its publication has been 
delayed. The two succeeding Parts — one on the vol- 
canic islands visited during the voyage of the Beagle, 
and the other on South America — will appear as soon 
as they can be prepared. 
May ‘2, 18-1?,. 
