396 M. P. de Grijs on the Faculty of 



LV. — Notes on the Faculty of Changing Colour in Reptiles. 

 By P. de Grijs *'. 



Undek the heading " Briefliche Mitteilungen " in no. 9 of the 

 last annual volume of ' Der Zoologische Garten ' there appears 

 a communication from Dr. A. Hanau on the coloration of the 

 interstitial integument in Tropidonotus ordinatus, var. sirtalis. 

 On reading the lines in question the thought involuntarily 

 occurred to me how little, after all, any observations are 

 capable of enlightening us as to the causes and efficacy of so 

 many phenomena in the animal kingdom. As the gentleman 

 referred to will undoubtedly have remarked, the question in 

 the case of T. ordinatus and all other species which have a 

 brightly coloured or marked interstitial integument is not of 

 a power of changing colour, but of fixed colours, which when 

 the body of the snake is not distended remain invisible owing 

 to the closely approximated scales. All the species of snakes 

 that I have hitherto observed possessed no trace of a power 

 of changing colour, such as is found in many other reptiles 

 and batrachians ; 1 have never read that snakes possessing 

 the power of changing colour have been observed, and I think 

 that I shall not be wrong in absolutely denying to this order 

 the faculty of sudden alteration of hue. Now what can be 

 the reason that no single snake possesses the power of changing 

 colour ? To these animals, as protection against enemies or 

 for the purpose of stealing upon their prey, a change of colour 

 would in many cases be of just as great advantage as to many 

 Lacertilia. Leaving out of the question the poisonous snakes, 

 which are sufficiently protected from attacks by their bite, 

 there still remains the great multitude of non-poisonous 

 species, which have many enemies. It is true that many 

 non-poisonous snakes possess great activity and swiftness; 

 but the same qualities are likewise shared by a large portion 

 of the Lacertilia which are able to change colour. I content 

 myself with having raised the question; it would be inter- 

 esting to bring about an exchange of opinions on the subject. 

 The fact that crocodiles and Chelonians are devoid of the 

 power of changing colour cannot reasonably create astonish- 

 ment; nature has furnished these creatures with sufficient 

 equipment for defence. But that among the snakes there 

 are no species at all with a more or less developed power of 

 changing colour is a fact that must attract our attention. We 



* Translated by E. E. Austen from ' Der Zoologische Garten,' xl. Jalirg. 

 no. 2 (1899), pp. 49-55. 



