s^bggestions as to insect colours and 2)atterns. 575 



effect of iridescence ; of the overflow of individuals from a 

 concealinof region into one less favourable — in all these we 

 have illuminating ideas which demand the fullest and 

 most respectful consideration. That they are sound prin- 

 ciples must, I think, be admitted at once ; but their relative 

 importance, the amount of ground which they cover, cannot 

 be decided offhand. I would only point out the extra- 

 ordinary frequency with which a continuous black colour- 

 ing unrelieved by pattern is accompanied by iridescence 

 or surface colours of some kind. In view of the wliole 

 drift of Mr. Thayer's interesting and most suggestive paper 

 it becomes probable that dead black would be too con- 

 spicuous even to many a well-armed aculeate or nauseous 

 Euploca, and that it is therefore modifl.ed so that it obtrudes 

 less upon the distant view of enemies which " mean 

 business." 



Although I have criticized some of the details of Mr. 

 Thayer's paper, I should wish again to point out that they 

 concern just those species which have not come under his 

 own eyes in the living state. Naturalists 0'>ve him a large 

 debt for the many new points of view and illuminating 

 suorcrestions contained in his memoir. 



December 24th, 1903. 



