COLOURATiUN OF REPTILES AND AMPHIBIANS. 26/ 



When we look at certain lizards and frogs, apart from their 

 surroundings, we find it diHicult to realize that such variegated 

 objects can be anything but conspicuous, but as a matter of fact 

 these ver}- markings Avhich we would consider as detrimental to 

 concealment only help \o make the possessor all the more secure. 

 To those who see the creatures only in museums this general 

 likeness to the surroundings is not evident. The conceahr:fnt 

 brouglit about by general protective resemblance can onh' be ap- 

 preciated by studying nature in its natural haunts. Referring 

 to this matter, Prof.Poulton, on page 24, " Colours of Animals," 

 says : " We cannot api)rcciate the meaning of the colours of many 

 animals apart from their surroundings, because we do not com- 

 prehend the complicated artistic effect of the latter." 



The variability in colouration displayed by Aoaiiia nculcata 

 in response to dift'erent surroundings is really remarkable. 



A male and female of this species may occupy the same tree, 

 Init I have never noticed two of the same sex so situated. The 

 male on such occasions goes right to the top of the tree, facing 

 the sun. The colour dorsally is then very varied, some specimens 

 being very light with various marblings, while others, on the con- 

 trary, are dull, possibly in sympathy with the lights and shades 

 beneath and around. 1 have never noticed the female go to the 

 topiuost branches of a tree, she seems to content herself with re- 

 maining in the deeper shadows. She is then a very dark brown 

 dorsally with slaty-blue patches here and there, having dark 

 longitudinal vcrmiculations ventrally. It is noteworthy that 



when the colours of either sex are dark dorsally, the Avhole ventral 

 surface is covered with these dark vermiculations. 



On the ground even a greater range of colour is exhibited, 

 inasnmch as all dorsal markings ma}' become obliterated in favour 

 of a very dark brown or a light yellow ( females evidently do not 

 po5sess the power of |)roducing" this latter colour), although 

 ventrally the shoulders and chest are a brick red and the throat a 

 deep blue, almost black. The dorsal surface of the female ma}- 

 be either dark browm, dull uniform grey, or different shades of 

 reddish brown, with various markings and marblings accord- 

 ing to the environment. 



When on the ground the adults often remain quite motion- 

 less until they are in danger of being trod upon ; their colour is 

 so much in accordance with the prevailing colours of the sur- 

 roundings, that an average passer-by would fail to notice them 

 if they did not move. On such occasions the intensity of the 

 ground colour and super-imposed light markings may vary con- 

 siderably according to the lightness or darkness of the sur- 

 roundings. 



This chameleonic power of colour adjustment seems to be 

 common to most of the Agamas. During the summer of 1908 

 I was fortunate enough to come upon a vivid green female 

 A. Iiispida in a field of young lucerne near Somerset Strand. 

 The creature harmonized so perfectly with the bright green of the 

 surroundings that, had it not moved from my feet, I should cer- 



