PREFACE i 
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. 
Lonvon, Jfarch 1891. 
