Chap. V. COLOURS OF ANIMALS. 207 



vorous insects, and these draw in their train the preda- 

 cious 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 num- 

 bers 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. jDallipes 

 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 



