74 SAURIA. CHAM^LEONID^. 



from a species found in Central Africa by the 

 occipital keel reaching forward to the centre of 

 the eye, by the back of the head being only 

 slightly lobed, and by the frontal scales being 

 tubercular. It is spread over the whole north of 

 Africa, and the south of Asia, and is said to 

 extend even into Spain. 



The changes of colour to which this reptile is 

 subject are so curious as to have attracted popular 

 observation from early times ; and though much 

 of fable has been mingled with the descriptions 

 of the phenomenon, it is still exceedingly in- 

 teresting ; and not the less so because of the 

 obscurity which has huug over the causes of the 

 changes, baffling the researches of acute physi- 

 ologists, and giving rise to many diverse theories. 

 The popular notion is that the Chameleon assumes 

 the tint of the surface on which it rests, becom- 

 ing green on a leaf, brown on the branch of a 

 tree, white on a stone, &c., but this opinion is 

 at variance with fact, and is now universally ex- 

 ploded by naturalists. Hasselquist, who consi- 

 ders the changes to be the result of a kind of 

 disease, remarks, that he never observed the Cha- 

 meleon assume the colour of an external object 

 presented to its view, although he made several 

 experiments for the purpose. He says that its 

 natural colour is an iron grey, or black mixed 

 with a little grey. This it sometimes changes, 

 and it becomes entirely of a brimstone yellow, 

 which, except the former, is the colour it most 

 frequently assumes. It sometimes takes a darker 

 or greenish yellow, and sometimes a lighter. 

 He did not observe it assume any other colours, 

 such as blue, red, purple, &c. When changing 



