390 MIMICRY IN THE COLORS OF INSECTS. 
layers in good preservation. The destruction of insects, which is 
so peculiar to the secondary strata in England, proves, as I be- 
lieve, that the bodies of the insects must have floated a very long 
time before they were deposited. It is quite a rarity to find well 
preserved insects there although many very well preserved wings 
even of lace-winged flies have been described. 
There is an interval after the transformation before the mem- 
branes of the wings become inseparably glued togethers it is at 
this time that the finishing of the colors takes place. For instance 
in an Aschna, a Libellula depressa or trimaculata, if the wing is cut 
off at the base, the two layers can be easily separated by manipu- 
lation under water, and the wing can be inflated with a little tube — 
by separating the borders with a knife. I can show specimens 80 
prepared. But this is only possible as long as the wings possess 
the appearance of having been dipped into mucilage, an appearance 
which is well known in young Odonata. 
The scales have just the same development as the wings. At 
first they are little open sacs, communicating with the hollow of 
the wing and the whole body, and at a later period are glued 
together like the wings themselves. 
In the wings and in the scales the hypodermal colors are formed 
and finished before the wings stick together, and by this means 
they are well preserved and safely encased. They have no pies 
communication in the glued parts with the interior of the animal, 
and are preserved in the same way, as if hermetically inclosed in & 
glass tube. There are even here in the wings and scales many 
epidermal colors, chiefly the metallic ones; but all the brighter 
colors (for instance the somewhat transparent spots in the ely pe 
of the Lampyridæ, Cicindelidæ, etc., and in the greater number 
Lepidoptera) are, as I believe, hypodermal colors. iii 
Finally there sometimes occurs outside of the animal, that 1$, on 
the epidermis, a kind of color which I consider as hypode ete 
color, such as the pale blue on the abdomen of many Odonata, die 
white on the outside of many Hemiptera, the pale gray a8 
elytra and thorax of the Goliathus beetle, the powder on i 
others. Some of these colors are very easily resolved in è ee 
_ and are apparently a kind of wax. I believe that these a 
produced by the hypodermis and are exuded through — 
channels of the pores (Poren Cancle). ; 
The hypodermal colors are very often different ™ 
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