PREFACE 



mittee of the Zoological Society of London, as well as to the 

 individual writers in whose works they first appeared. 



The authors have further much pleasure in acknowledging the 

 ready and obliging way in which Mr. Oldfield Thomas has, 

 throughout the progress of the work, placed his extensive know- 

 ledge of the group of animals of which it treats at their disposal. 



London, March 1S91. 



