42 NATURAL SELECTION III 
to the branches, that until it moves it is absolutely invisible ! 
An allied species (O. concentricus) is found only at Para, on a 
distinct species of tree, the bark of which it resembles with 
equal accuracy. Both these insects are abundant, and we 
may fairly conclude that the protection they derive from this 
strange concealment is at least one of the causes that enable 
the race to flourish. 
Many of the species of Cicindela, or tiger beetle, will 
illustrate this: mode of protection. Our common Cicindela 
campestris frequents grassy banks, and is of a beautiful green 
colour, while C. maritima, which is found only on sandy sea- 
shores, is of a pale bronzy yellow, so as to be almost invisible. 
A great number of the species found by myself in the Malay 
islands are similarly protected. The beautiful Cicindela 
gloriosa, of a very deep velvety green colour, was only taken 
upon wet mossy stones in the bed of a mountain stream, where 
it was with the greatest difficulty detected. A large brown 
species (C. heros) was found chiefly on dead leaves in forest 
paths ; and one which was never seen except on the wet mud 
of salt marshes was of a glossy olive so exactly the colour of the 
mud as only to be distinguished, when the sun shone, by its 
shadow! Where the sandy beach was coralline and nearly 
white, I found a very pale Cicindela ; wherever it was volcanic 
and black, a dark species of the same genus was sure to be 
met with. 
There are in the East small beetles of the family Bupres- 
tide which generally rest on the midrib of a leaf, and the 
naturalist often hesitates before picking them off, so closely 
do they resemble pieces of bird’s dung. Kirby and Spence 
mention the small beetle Onthophilus sulcatus as being like 
the seed of an umbelliferous plant; and another, a small 
weevil, which is much persecuted by predatory beetles of the 
genus Harpalus, is of the exact colour of loamy soil, and was 
found to be particularly abundant in loam pits. Mr. Bates 
mentions a small beetle (Chlamys pilula) which was undis- 
tinguishable by the eye from the dung of caterpillars, while 
some of the Cassidz, from their hemispherical forms and pearly 
gold colour, resemble glittering dew-drops upon the leaves. 
A number of our small brown and speckled weevils at the 
approach of any object roll off the leaf they are sitting on, at 
