suggestions as to insect colours and patterns, 575 
effect of iridescence ; of the overflow of individuals from a 
concealing 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 whole 
drift of Mr. Thayer's interesting and most suggestive paper 
it becomes probable that dead black would be foo con- 
spicuous even to many a well-armed aculeate or nauseous 
Huploea, and that it is therefore modified so that it obtrudes 
Jess 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 owe him a large 
debt for the many new points of view and illuminating 
suggestions contained in his memoir, 
