COLOUR VARIATION IN LIZARDS 123 



much as it has been by some supposed to be poisonous, 

 whilst others have failed to detect any evidence of 

 poison glands. If it be poisonous, it is the only genus 

 that is so amongst lizards. The species noted is 

 characterised by a series of rings on the limbs and 

 on the tail. With increasing age these rings become 

 broken up, and the pattern becomes an irregular coarse 

 network of a blackish colour. 



In the genus Gerrlionotus, the young individuals are 

 much more brilliantly coloured than adults, and have 

 a more distinct colour pattern of alternating light and 

 dark cross-bars. On young individuals were proposed 

 the species G. cceruleus and G. ivebhii. The colours 

 fade out with increasing age and maturity in most 

 species of this genus, becoming shades of olive or 

 brown with lateral bars ; or if the brilliant colours are 

 retained as in two other species, G. gramineus and 

 G. auritus, the cross-bars disappear. 



Occasionally it is found that age is responsible for 

 an apparently quite new arrangement of markings and 

 colours, but, when this is the case, careful investigation 

 shows that there are intermediate steps in the process 

 as the age advances. 



Thus, in the genus CnemidopJwrus, a genus in which 

 it is most difficult to discriminate the species, the 

 colour markings differ in the same individual at 

 different ages, and, what is still more interesting, the 

 age at which the adult colouration is attained appears 

 to vary in different localities. Some of the species. 



