Page:The naturalist on the River Amazons 1863 v1.djvu/231

 vorous insects, and these draw in their train the predacious 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 Caripí 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 beaches 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