IV THE COLOURS AND PIGMENTS OF CCELENTERA 87 



tufts of fine, brightly-coloured moss, or, yet more 

 appropriately, certain varieties of the very finely 

 divided leaves of cultivated parsley." So also one 

 of the species of mushroom coral, Fungia crassiten- 

 taculata, when in the fully extended condition, " bears 

 a considerable resemblance to a crowded growth of 

 the common green seaweed, Enteromorpha." There 

 is, however, great colour-variation in the species, and 

 it is only the green variety which presents this 

 appearance. Finally, we may mention the case of 

 the " lettuce-corals " {Tridacophyllid), which, especially 

 in the green species, are said to closely resemble in 

 their peculiar method of growth leaves of lettuce or 

 endive. This is an interesting case of resemblance, 

 for it would require an exceedingly enterprising 

 biologist to construe it as a case of protective or 

 alluring coloration. 



The Effect of Light upon the Develop- 

 ment OF Pigment 



On this subject there are a few interesting observa- 

 tions. Mr. Saville Kent observed that in Euphyllia 

 glabrescens the tentacles were frequently green or brown 

 with paler tips, but where they were completely shaded 

 from the light they were quite transparent and 

 colourless with faintly tinted tips. Similarly, forms 

 like Symphyllia which only unfold their tentacles at 

 night, have these transparent or colourless, while the 

 exposed parts are coloured with the usual brown or 

 green pigments. As a curious exception to this rule 

 he found that a species of Dendrophyllia, D. coccinea, 

 was always coloured a bright red, even when shaded. 



