84 COLOUR IN NATURE chap. 



variation. Most frequently it is a dark brown colour 

 with white extremities ; sometimes the whole surface, 

 including the polypes, is a vivid grass-green. Mr. 

 Saville Kent describes a large colony which when 

 first examined was pinkish-brown with greenish- 

 white growing apices, the polypes throughout being 

 a light emerald - green. On revisiting the colony 

 after two years, it was found that the surface of the 

 colony was of a clear seal-brown with white or pale 

 lilac-blue tips, while the polypes were a clear red- 

 brown, the tips of the tentacles only being a greenish- 

 white. This variation is exceedingly marked, but 

 the author seems to intimate that it was accompanied 

 by a retardation of the growth of the colony. It is 

 unnecessary here to give further details as to the 

 colouring of the Madrepores ; the above descriptions, 

 which are taken almost verbatim from The Great 

 Barrier Reef, are sufficient to prove the statement 

 that these corals are remarkable for their contrast of 

 colour, the contrast being produced by the respective 

 colours of polypes and ground-substance, or by the 

 different tints of mature and growing regions. The 

 colours mentioned are exceedingly common through- 

 out the genus. 



The same brilliancy of tint is observable among 

 the other corals ; the banding of the surface of 

 individuals is especially remarkable among the large 

 sea-anemones or the solitary corals. The occurrence 

 of bands of colour, especially round the tentacles, is 

 admirably shown in many of our native sea-anemones, 

 as are also the essential peculiarities of colouring. 

 Note, for example, the green and magenta colouring 

 of Anthea cereus, the bright turquoise beads at the 



