INTRODUCTION. XV 



red. At the same time, a very large number of our southern forms 

 show a latent tendency to red, and, in fact, occasionally become red, 

 but under certain conditions of "natural selection." In other 

 words, in certain localities, the red forms are almost entirely absent, 

 whilst in others, with a different environment, the red is almost the 

 only form produced. This species also shows every transition through 

 red and brown to black. Another species showing the upward tendency 

 of green to form red and brown is Banksia argentula. Here, the 

 normal green of the anterior wings of this species is frequently de- 

 veloped into a distinct red-brown. An exactly similar tendency is seen 

 in the sexually dimorphic condition of Smerinthus tilice, in which 

 species the males are usually more or less green, the females more or 

 less red. The green in normal Miselia oxyacantJice is changed into red- 

 brown in the variety capucina and its intermediate forms. Cidaria 

 psittacata, Epunda lichenea, Hadena atriplicis, H. protea and others ex- 

 hibit a similar tendency. These are apparently all direct progressive 

 forms of variation, or they exhibit a progressive tendency, with the 

 exception of Ellopia fasciaria var. prasinaria, in which the normal red 

 develops a green variety, the variety therefore being retrogressive. I 

 have a natural dark brown variety of Aplecta herbida (prasina), which 

 shows the tendency of green to brown as well as red. Perhaps the 

 parallel development of deep brown and green from yellow, is best 

 seen in Triphcena fimbria. The typical coloration in Britain of the 

 fore wings of this species is pale ochreous yellow, a very unstable and 

 easily changed pigment so far as this species is concerned. Reddish- 

 ochreous varieties are not uncommon, and these develop frequently a 

 dark green form known as var. solani, side by side with a deep mahog- 

 any-brown form (var. brunnea), whilst frequently the same specimen 

 is partly green and partly red-brown. JSo species, I think, shows 

 more distinctly the intimate connection between red and green. 



A species, the green of which is closely allied to red, is Euchelia 

 jacobcece. Similar as is this species superficially to Cattimorpha, their 

 pigments are as different as possible, the red of the latter genus having 

 come through yellow, whilst that of Euchelia apparently comes through 

 green. Hence the red of jacobcece is very soluble as also is its green, 

 but whilst the red is soluble enough in its allies, the green is perfectly 

 unassailable. If jacobcece be bleached, the green and red become almost 

 equally pale, and both are quickly reduced to a dirty yellowish or 

 greyish, the red parts differing in no way from the green in colour 

 except that they are a little paler, but no bleaching appears to alter the 

 green of Callimorpha. 



But I am inclined to suggest quite another origin to the apparent 

 dark green in the upper sides of Argynnis paphia var. valesina, which 

 obviously owes its development to the same causes as those which bring 

 about the dark females of Argynnis aglaia f found in our own moorland dis- 

 tricts. Since the normal females of both A. paphia and of A. aglaia 

 in Britain, show equally a similar but less strongly developed coloration 

 to the typical males, so the var. valesina and moorland females of A. 

 aglaia show the same further retrogression of coiciiir which becomes 

 excessively pale on the costal and outer margins. At the same time 

 this retrogression in pigment is accompanied by a decided and palpable 

 increase in the development of non-pigmental blackish scales. These, 

 in both species, show a tendency to give a more or less distinctly 



