xiv. 



definite names for the parts, rather than such obscure 

 phrases as " medio dorsal process" and the like, which 

 to the bewilderment of the reader frequently occur in 

 what would otherwise be valuable contributions to the 

 study of the genitalia. 



During the course of my preparations for the present 

 work I have been most fortunate in having the indefati- 

 gable assistance of niy valued friend, the Kev. C. E. N. 

 Burrows, F.E.S., to whose generous co-operation I owe 

 more than I can express, and to whom the production of 

 this work in a comparatively short period of time is largely 

 due. During the past six years our correspondence has 

 been almost a daily one, indeed it was an unusual event 

 not to find a letter from him on the breakfast table, and 

 often a second would arrive during the course of the day. 

 As was natural in such an investigation as this, we could 

 not always see eye to eye, and I cannot say too much of 

 Mr. Burrows' patience, whilst his kindly nature was 

 revealed in the care with which he explained his views, 

 illustrating his points with the neatest of little sketches, 

 until at last agreement was reached. When unusually 

 knotty questions arose and letters failed to elucidate 

 matters, it was often necessary for me to journey down 

 to see him. On all such occasions I was welcomed at his 

 home with its wonderful garden where he has taken so 

 many rare and notable species. There Mr. Burrows has 

 again and again proved himself to be not only a man of 

 science, but also a most genial host, and my visits will 

 always remain as red letter days in my memory. I 

 rejoice to take this opportunity of expressing my deep 

 debt of gratitude for all that his friendship has meant 

 during these six years of unceasing co-operation. 



In the course of preparing the present work, Mr. 

 Burrows and I have each made a complete set of mounts 

 of all the species of the Geometrida, and in a large number 

 of cases several mounts of the same species. This has 

 been an additional safeguard in securing accuracy, besides 



