ASSIMILATIVE COLOURATION. 457 
day by day poured out from countless chimneys, this moth “has 
during the last fifty years undergone a remarkable change. The 
white has entirely disappeared, and the wings have become totally 
black, so black that it has obtained the cognomen ‘negro’ from 
naturalists.” * The dipterous insect Ce@lopa frigida undergoes 
its transformations in the black sea-weed cast up by the spring 
tides. The flies and also the pupe are black.t In a revision of 
the American orthopterous genus Spharageomon, Mr. Morse 
states: “‘ Variation in colour in this genus, in common with other 
Ciidipodine, counts for very little; the same species or race may 
be of all shades from a general dark fuscous to a pale buff or 
even a bright reddish brown, even in specimens from the same 
spot, yet it is probable that the general tint of a large series will 
be found to agree with the colour of the soil of the locality, or 
other peculiarity of environment. Specimens of different species 
from different localities in Colorado show a striking reddish 
almost rosaceous colouration due to some such cause.’ { Of 
course this can only apply to the insects when at rest, otherwise 
their more gaily-coloured under wings would contradict the view 
advocated. A previous American writer, Mr. Brunner, had pro- 
posed that climatic differences had accounted for the varied 
colouration of the wings of some North American Locusts.§ 
Eimer has some excellent observations on this point, and with 
these insects :—‘‘ The Grasshopper with red hinder wings banded 
with black, which is so common with us (in Germany) in summer, 
Acridium germanicum (Cidipodea germanica), when it occurs on 
the reddish brown Triassic clay of Tubingen, resembles this 
ground so closely with its wings folded that it cannot be distin- 
guished from it. A little above the clay on the hills of this 
neighbourhood there occurs a whitish sandstone, sometimes only 
for the breadth of a path or in somewhat larger surfaces, fre- 
quently surrounded by the former. On these small patches of 
lighter ground I find regularly only Grasshoppers with quite light 
upper wings, so that they can scarcely be distinguished from the 
soil. And I have elsewhere observed the same remarkable 
* Tutt, ‘ British Moths,’ pp. 144, 149, 179, 305. 
+ Miall, ‘Nat. Hist. Aquat. Ins.,’ p. 373. 
t ‘Psyche,’ vol. vii. p. 288. 
§ ‘Science,’ 1893, p. 133, 
