APPENDIX A 



(Professor E. B. Poulton has kindly given us permission to append the follow- 

 ing very remarkable addition to our subject.) 



[Extracts from] A few Notes on South African Chamaeleons, &c. By G. B. 

 LoNGSTAFF, D.M., M.A., of New College, Oxford, and Edward B. 

 Poulton, D.Sc, M.A., F.R.S., Hope Professor of Zoology in the Uni- 

 versity of Oxford, and Fellow of Jesus College, Oxford.* 



The following observations were made during the visit of the British 

 Association to South Africa in 1905. The conditions were not favourable to 

 continuous investigation: nevertheless, I believe that some of these scattered 

 notes are not without interest, especially those referring to the automatic 

 adjustable countergrading of shadow on the two sides of the chamaeleon. It 

 is probable that the independent control of the colours of the two sides of the 

 body has been often observed before, but, so far as I am aware, this is the 

 first attempt to explain the significance of the power. The illuminating 

 effect of a great hypothesis like that of Mr. Abbott H. Thayer's in the realm 

 of protective coloration is well seen in the fact that Dr. Longstaflf, Professor 

 C. V. Boys, and the present writer independently grasped the meaning of the 

 colour-change the moment it took place before their eyes. I do not know 

 whether my two friends have studied Mr. Thayer's writings or examined his 

 beautiful models at London, Oxford, or Cambridge,! but I have no doubt that 

 it is the result of his work that interpretation was "in the air." 



I have to thank Mr. G. A. Boulenger, F.R.S., for kindly naming the 

 specimens upon which the following observations were made. — E. B. P. 



* (Read 7th March, 1907.) [Printed in the Linneari Society's Journal — Zoology, Vol. XXX, 

 October, 1907.] 



t [I was familiar with Mr. Thayer's models. — G. B. L., July 17, 1907.] 



241 



