AUTHOR’S PREFACE

I became partly acquainted with the districts of which the present volume treats as a member of the Anglo-German Yola-Chad Boundary Commission in 1903-4.[4] In endeavouring to inform myself with regard to the region then traversed, I found it a great inconvenience that the standard works, which contain descriptions of the former Sultanate of Bornu—works which are comprehensively ponderous—suffer from being very unhandy, and that, owing to the fact of their being published a generation ago, cannot include the latest investigations. Moreover, the literature of the last ten or twenty years on this subject being very scattered, the study of a highly interesting district is rendered unusually difficult. No monograph on it has hitherto existed.

I have now attempted in the present book to comprehend in such a monograph the essentials of the literature already known and of my own observations, which can correct particular errors in zoology and botany and will also deal generally with all lines of inquiry.

I have been most kindly assisted in my work by a whole number of gentlemen, who have helped me with information in the kindred sciences of zoology and botany, who have enabled me to examine the comprehensively ponderous literature, who have answered various questions, or who have simply given me advice and suggestions. They are Drs. Marquardsen and Moisel, Professor Reichenow, Professor Volkens of Berlin, Professor Rein of Bonn, Herr G. Seligmann of Coblenz, Professor Boettger of Frankfurt a/M., Professor Lacroix of Paris, and Professor Aurivilius of Stockholm. It is my pleasant duty to render them herewith my heartiest thanks.

Bonn, March, 1910.