r. MIGRATION AFFECTED BY THE ENVIRONMENT. 4-"> 



between colour and locality is shown by the fauna of Ceylon ; 

 there is a great prevalence of green* among the insects of that 

 island; Haeckel pointed out that this might be merely pro- 

 tective: in a forest country it is not surprising to meet with 

 green as a prevalent colour. 



But green is not confined to the forest fauna; it is quite 

 common also among the marine animals; and though there are 

 abundant alga? in those seas, green is not altogether so common 

 a colour among the inhabitants of the sea as it is among the 

 inhabitants of forests. Besides, animals which seldom show 

 any green in other localities are green here : for example, sea- 

 urchins, brittle-stars and star-fish, among which various 

 shades of brown, purple and red are as a general rule the pre- 

 vailing colours. Particularly is this the case with corals, which 

 are not often green. Ransonnet, in his work upon Ceylon, gives 

 two beautiful plates which represent life upon a coral reef, and 

 which were sketched by the author from a diving-bell ; green 

 is the only colour which is at all prominent in these plates, and 

 is not by any means confined to the Corals. 



Professor Haeckel f himself, though inclined to put down the 

 green to the necessity for protection, admits that the pre- 

 valence of green among the corals is a very remarkable and 

 noteworthy fact. He speaks, in describing a coral reef, of 

 " a yellow-green Alcyonia growing with sea-green Heterojjora, 

 and malachite-like Anthophylla side by side with olive-green 

 MiUt'i>ora; Madrepora'dndAstrtea, of emerald hue, with brown- 

 green Monticulopora and Mceandrina." Even a species of the 

 gigantic clam Tridacna is green, and so are many other 

 marine creatures. Even if this particular instance may be 



* Even the great four-feet-long earthworm of Ceylon, which is usually 

 spoken of as blue, appears from Mr. Bourne's sketch to be green 

 j " Ceylon," p. 155. 



