172 THE INFANCY OF ANIMALS 



where the young are sombrely coloured, while the adult is 

 more or less handsomely marked. Thus the young of the 

 common lizard {Lacerta vivipard) are nearly black, the 

 adults are brown or reddish and spotted. No less mysteri- 

 ous, at first sight, are those cases where the stripes of the 

 young are retained in the adult female, but lost in the 

 male, as in the case of the green lizard (Lacerta viridis), 

 for example. But this also obtains in the case of many 

 birds, as we have already shown. 



A remarkable case of colour change, wherein the pattern 

 is reversed during the transition from youth to age, is 

 found in an African snake known as Grayia ornata. In the 

 young stage, which was originally regarded as an adult 

 subspecies of Grayia ornata, the body is black, with 

 broad whitish or greyish transverse bars, which split on 

 each side so as to form a series of reversed Y's, each Y 

 being slightly speckled with black about the middle line. 

 With advancing age the black ground changes to grey or 

 brown ; whereas the Y's show more and more black until 

 they have only white margins, and even these eventually 

 vanish. Consequently the fully adult snake has black 

 markings on a grey ground in place of the light markings 

 on a black ground characteristic of the young ; in other 

 words the colour pattern of the adult is exactly the reverse 

 of that of the young. 



The snakes of the genus Coluber are remarkable for the 

 fact that the coloration of the young differs entirely from 

 that of the adult, and both stages are strongly coloured. 

 This transformation is well illustrated in the case of the 

 chicken snake {Coluber quadrivittatus) . At the time of 

 hatching it is greyish, decorated with a regular series of 

 oblong blackish saddles. As it approaches maturity the 

 body colour changes to yellow, a dark stripe appears on 



