xiv INTRODUCTION. 



with the steel plates which had been prepared by the 

 late Mr. E. W. Robinson to illustrate it, and have 

 found myself at great disadvantage in taking it up 

 again after such a lapse of time. The plates them- 

 selves had become rusted, and could only be utilized 

 by printing first on stone, instead of working direct 

 from the steel ; this has impaired the clearness of 

 the delicate outlines in some cases, but I trust that 

 in the colouring this will be found to have been 

 remedied. 



Whilst rendering my grateful acknowledgment 

 to Prof. P.- C. Zeller for his kind and courteous 

 replies to numerous queries which I have addressed 

 to him, and for the great assistance I have 

 derived from them, I must crave indulgence for 

 many and serious shortcomings in this humble 

 attempt to add to the knowledge of a somewhat 

 difficult group of insects. 



WALSINGHAM. 



April 26th, 1880. 



