conclusively proving how small is the variation that exists 

 between different mounts of the same species. The first 

 sketches were made by Mr. Burrows from the most 

 perfect of the mounts by means of the Camera Lucida, 

 whilst the descriptions were written with the aid of all 

 the material at our disposal. As the females showed well 

 marked differences, the salient features of the genitalia 

 in this sex have been added (on the left of each figure), 

 and they have helped to elucidate the relationship between 

 species where the male organs exhibited great divergence 

 of form. I am still of the opinion that drawings are 

 preferable to photographs, as the latter, by showing too 

 much, make it difficult to grasp the significant points. 



As the penis forms an important, in many cases the 

 most important, structure for purposes of differentiation, 

 drawings of this organ have been added (on the right of 

 each figure), but I would warn workers that it is 

 extremely 'difficult in this case to get uniformity of 

 position. 



I have again adopted the plan of placing the name 

 of the species beside each drawing, and I regret that ibis 

 has not been done by more writers, whilst I am glad to 

 be able to refer to a notable exception in Dr. Eltringham's 

 splendid article on the group Acraea, published in the 

 Transactions of the Entomological Society of London, 

 1913. 



The methods of preparation were fully described 

 in the " Noctuidse," and to this work I would refer my 

 readers. The only improvement I can suggest is in refer- 

 ence to staining, which is of great assistance. So far 

 we have found a difficulty in obtaining a permanent stain, 

 but the cause of the failure seems really to be due to the 

 imperfect removal of the Caustic Potash. On the 

 suggestion of Mr. Burrows, citric acid was employed in 

 the washing process with very good results. If this point 

 be attended to, Stevens' green ink will be found to be a 

 very satisfactory stain. 



