delineation, but after photographing some two hundred 

 preparations, I found that they were not suitable for my 

 purpose. Firstly, owing to the great transparency, 

 including both upper and under surfaces, which instead 

 of elucidating the structure, simply bewildered and 

 confused the picture. Secondly, on account of the great 

 difficulty in getting the preparations exactly balanced. 

 In drawing it was possible to exclude extraneous parts 

 and rectify misplacements and so produce a figure, 

 that would be much simpler and more correct for 

 comparison. 



I now regret that I did not include the penis in the 

 figures, as it is often of the utmost importance in 

 critical cases ; but at first I did not estimate this organ 

 at its true value, and the confusion produced by its 

 central position, coupled with the extreme difficulty in 

 getting anything like uniformity, owing to the softness 

 of the structure and the .difficulty of extroverting the 

 eversible parts, has made me feel that a short 

 description is even better than a drawing, which as 

 often as not, might be misleading. 



I have adopted the scheme of placing the name of 

 the species beside each drawing. This deviation from 

 the ordinary numbering of the figures (which necessitates 

 having to turn to another page for an explanation) will I 

 am sure be appreciated as an important saving of time. 



For supply of specimens, both local and rare, I 

 wish to express my warmest thanks to our British 

 Lepidopterists all over the country, without whose help 

 I could never have got the work to its present complete 

 state, and I wish here to place on record my grateful 

 thanks to my old and valued friend Samuel James 

 Capper, the veteran and life long president of the 

 Lancashire and Cheshire Entomological Society, and 

 not less to E. R. Bankes, G. T. Porritt. W. G. Sheldon, 

 Louis B. Prout, Dr. T. A. Chapman, J. W. Tutt, 



