236 COLOUR IN NATURE 



Colours of Reptiles, especially Lizards 

 AND Snakes 



Among Reptiles the colours are most conspicuous, 

 and have been most studied among snakes and 

 lizards. In lizards black, gray, brown, and green 

 are common colours, while most display very distinct 

 and constant markings. According to Eimer the 

 typical ground plan of the dark markings consists of 

 seven longitudinal bands. The pigments seem to 

 consist of the dark " melanins " and lipochromes, the 

 green colour of, e.g., the green lizard being not due 

 to a green pigment but to the structure of the skin, 

 and to the contained yellow and black pigments. 

 According to Krukenberg lipochromes are rare or 

 perhaps absent in snakes, while melanins largely 

 predominate. Yellow pigments do occur freely in 

 snakes but their nature is undetermined, probably 

 they are merely altered lipochromes ; for the peculi- 

 arities which Krukenberg enumerates may be due to 

 impurities or to decomposition. Lizards frequently 

 exhibit the type of coloration known as protective, 

 and, as is well known, have often considerable power 

 of colour-change, best exemplified in the chameleon. 

 It is interesting to note that the aberrant poisonous 

 lizard Heloderma diverges markedly in colour from 

 other lizards, being vividly marked with black and 

 yellow, instead of showing the sober greenish hues 

 of most lizards with their beautiful but unobtrusive 

 striping. In its histological characters the skin of 

 lizards shows much similarity to that of the frog, the 

 power of colour-change, when present, being again due 



