PEOTECTIVE COLORATION. 121 



in green, yellow, and black; and Ij'ingin a museum its glitter- 

 ing coils certainly form a most striking object. But in nature 

 the puff-adder has a very different background. It is essen- 

 tially a forest animal, its true habitat being among the fallen 

 leaves in the deej) shade of the trees by the banks of streams. 

 Now, in such a position, at the distance of a foot or two, its 

 appearance so exactly resembles the forest bed as to be almost 

 indistinguishable from it," 



The puff-adder does not specially resemble fallen leaves, but 

 among the variety of objects in the situations which it affects 

 it escapes notice. The colours cannot be exactly protective, 

 because the reptile .does not 'always conceal itself in such 

 situations as Mr. Drummond describes. It often lies half 

 buried in sand, and would not probably be very conspicuous 

 then. 



I refer later (p. 257) to the sexual differences in this reptile, 

 which are not consistent with a theory of protective resem- 

 blance, but are thoroughly consistent with the view that 

 concealment is effected by frequenting situations where the 

 ground is broken and varied in colour by living and decaying 

 vegetation of all kinds. 



Colours of Pelagic Organisms.' 



The surface of the sea, whether near to shore or in mid 



ocean, appears to any one looking down from a boat almost 



devoid of animal life ; from time to time a solitary medusa or 



a shoal of these animals will be seen, and less frequently 



some of the rarer surface organisms will break the monotony ; 



but with these exceptions the water appears to be absolutely 



free from living creatures. 



* A general account of the pelagic fauna may be found in Moseley's 

 " Naturalist on the ChuUe'nfjt)-'' and in Agas^iz, '■ Three Cruises of the 

 Blake:' 



