n 



Kent, and the environment of A. palustris in the marshes of 

 Algeria and Kent, are respectively nearer to each other and 

 more continuous than are the environments of A . trifolii in 

 the meadows and A. palustris in the marshes of Kent, or 

 those of A. seriziati in the marshes and A. syracusia in the 

 meadows of Algeria. There is really a greater discontinuity 

 in the environment of the Kent A. trifolii and the Kent A. 

 palustris than between the Kent A. trifolii and the Algerian 

 A. trifolii (= A. syracusia). 



If I appear to be taking my illustrations from a group not 

 generally well known, I would urge two excuses for doing so : 

 (i) that in the book I have recently written I have worked 

 out the natural history, habits, and distribution of the 

 Anthrocerids in considerable detail ; (2) that I have recently 

 exhibited at the meetings of this Society the various species 

 and forms to which reference has been made ; but, as 1 have 

 already pointed out, illustrations might just as well be taken 

 from almost any other family of the Lepidoptera whose 

 species are in a state of flux — the Erebiids, the Brenthids, 

 and the Melitseids would furnish many such, and my study 

 of these as well as the Anthrocerids tends to show that 

 environmental conditions are the primary causes of the 

 development of so-called specific differences, the actual 

 difference in kind which marks off well-defined species from 

 their nearest allies being due to isolation by habit, food-plant, 

 or some other outward manifestation of an actual difference 

 in the organism, and which tends to intensify any 

 peculiarity of colour, form, &c, to which the new form may 

 be subject. It becomes clear, therefore, that we must define 

 environment to obtain a clear insight into what this means. 

 It is not sufficient to assume, because Algeria and the 

 British Isles are some degrees of latitude from each other, 

 that the environmental conditions of a species common to 

 both countries must be very dissimilar. They may be, of 

 course, but they may also be almost identical except in the 

 matter of temperature and the influences arising therefrom. 

 But temperature is only one factor of a long series, and the 

 environment of an exposed chalk-hill and the wood that 

 clothes its summit is probably far more dissimilar than a 

 meadow in Southern Sweden and a somewhat similar meadow 

 in Northern Africa. 



What factors, then, constitute the environment which 

 makes up the sum total that, in their effects, we consider so 

 potent in their influence in the modification of animal and 

 plant life ? The factors are so numerous and the conditions 



