PREFACE.. vii 



cipally devoted to the examination and comparison of 

 these collections. The Government of India has not 

 only most liberally relieved him from his duties on the 

 Geological Survey, in order to enable him to prepare 

 the present work, but has also permitted him to com- 

 plete the same in England, in order to afford him 

 access to the museums and libraries of Europe. 



The Government of Bombay, under whose orders the 

 writer was acting whilst in Abyssinia, and for some 

 time subsequently, has also afforded him every facility 

 and aid. 



