REPTILIAN LIVERIES. 149 



combination with a modification of the outer 

 horny and colourless layer of the epidermis. 

 The green colour of some tree snakes, however, 

 appears to be due to a pigment, inasmuch as Mr 

 Boulenger, one of our greatest authorities on 

 Eeptiles, observes that green tree-snakes give 

 the colour of the alcohol in which they are 

 preserved a green tinge. 



Wholly white Eeptiles, it is interesting to 

 note, are unknown in an adult state, though it 

 must be remarked the newly-born chamseleon is 

 snow-white ; uniformly green, or blue, and black 

 are common. As a rule, however, the colours 

 are varied so as to produce a well-marked 

 pattern. 



The " resemblance colours," to which reference 

 was made at the beginning of this chapter, are 

 so called because they enable the wearers to 

 conceal themselves, by reason of their likeness 

 to the general surroundings. By this means 

 they are enabled either to escape their enemies 

 or to approach their prey unobserved. Since 

 the same type of coloration is adopted to gain 

 two very different ends, we can only tell 

 whether the livery of any particular reptile is 

 assumed for protective or aggressive purposes 

 after a careful examination of each case. Thus, 

 the green tree-frog is obviously protectively 

 coloured, whilst the green tree-snake is to be 

 regarded as aggressively coloured. Incidentally, 

 of course, the aggressively coloured reptile is 

 also protectively coloured. 



Though the real significance of the colours of 

 animals was not really grasped until within this 



