PREFACE. 



fully take place. To facilitate this, he has been careful to have 

 drawn, when possible, the actual types of original descriptions, and 

 no less than fourteen representations of such types have been here 

 figured. 



The author desires to express his warm thanks for the kind aid given 

 him by his scientific friends; especially by Professor Flower, C.B., 

 F.R.S., Dr. Giinther, F.R.S., Dr. P. L. Sclater, F.R.S., Mr. Blanford, 

 F.R.S., Mr. Oldfield Thomas, F.Z.S., and Mr. R. Lydekker, F.G.S. 



He also desires to record his grateful sense of the zeal, patience, 

 and skill with which his Plates have been executed by Mr. J. G. 

 Keulemans. 



Hurstcofce, Chilworth, 

 April 29th, 1890. 



