106 CARIPI AND THE BAY OF MARAJO. Cuap. V. 
In some respects the termites are more wonderful than the ants, but I 
shall reserve an account of them for another chapter. 
I amassed at Caripi a very large collection of beautiful and curious 
insects, amounting altogether to about twelve hundred species. ‘The 
number of Coleoptera was remarkable, seeing that this order is so - 
poorly represented near Para. I attributed their abundance to the 
number of new clearings made in the virgin forest by the native settlers. 
The felled timber attracts lignivorous insects, and these draw in their train 
the predaceous species of various families. As a general rule the species 
were smaller and much less brilliant in colours than those of Mexico 
and South Brazil. The species, too, although numerous, were not 
represented by great numbers of individuals ; they were also extremely 
nimble, and therefore much less easy of capture than insects of the 
same order in temperate climates. On the sandy beach I found two 
species of Tetracha, a genus of tiger-beetles, which have remarkably 
large heads, and are found only in hot climates. They come forth at 
night, in the daytime remaining hid in their burrows several inches 
deep in the light soil. Their powers of running exceed everything I 
witnessed in this style of insect locomotion. ‘They run in a serpentine 
course over the smooth sand, and when closely pursued by the fingers 
in the endeavour to seize them, are apt to turn suddenly back, and thus 
baffle the most practised hand and eye. I afterwards became much 
interested in these insects on several accounts, one of which was that 
they afforded an illustration of a curious problem in natural history. 
One of the Caripi species (T. nocturna of Dejean) was of a pallid hue 
like the sand over which it ran; the other was a brilliant copper- 
coloured kind (T. pallipes of Klug). Many insects whose abode is the 
sandy beach are white in colour; I found a large earwig and a mole- 
cricket of this hue very common in these localities. Now it has been 
often said, when insects, lizards, snakes, and other animals are coloured 
so as to resemble the objects on which they live, that such is a provision 
of nature, the assimilation of colours being given in order to conceal 
the creatures from the keen eyes of insectivorous birds and other animals. 
This is no doubt the right view, but some authors have found a difficulty 
in the explanation on account of this assimilation of colours being 
exhibited by some kinds and not by others living in company with 
them; the dress of some species being in striking contrast to the 
colours of their dwelling-place. One of our Tetrachas is coloured to 
resemble the sand, whilst its sister species is a conspicuous object on 
the sand ; the white species, it may be mentioned, being much more 
swift of foot than the copper-coloured one. The margins of these 
sandy beaches are frequented throughout the fine season by flocks of 
sandpipers, who search for insects on moonlit nights as well as by day. 
If one species of insect obtains immunity from their onslaughts by its 
deceptive resemblance to the sandy surface on which it runs, why is not 
its sister species endowed in the same way? ‘The answer is, that the 
dark-coloured kind has means of protection of quite a different nature, 
and therefore does not need the peculiar mode of disguise enjoyed by 
its companion. When handled it emits a strong, offensive, putrid and 
musky odour, a property which the pale kind does not exhibit. Thus 
