'38 



FORM AND COLOUR, 



commonly associated with cryptic colouring and is seen, for instance, in 

 the stick insect whose long and slender body is formed and coloured to 



FIG. 49. 

 Leaf Insect. 



resemble the twigs amongst which it lives ; we suppose this to be a 

 device to hide the insect from birds. So too in the Leaf Insect (fig. 49) 

 which bears an extraordinary resemblance to a bunch of green leaves. 

 The intensely hard spines found on some beetles and bugs, the thick 

 coating of hairs (fig. 50), the very thick hard masses of chitin, are 

 believed to make insects distasteful to birds and possibly to predaceous 



