PROTECTIVE COLOEATIOX. 131 



probable that tbe pigment is directly transferred to the skin, 



just as the skin of a man is discoloured by nitrate of silver 



taken as medicine; in tbe second place it is very significant 



that the red pigment is apparently present in addition to the 



normal pigments. If natural selection had in the course of 



long ages brought about the colour resemblance between the 



fish and their surroundings, it would be, one might fairly 



imagine, rather by an alteration of the existing pigment than 



by the formation of a fresh pigment red in colour, deposited 



side by side with the original pigments. It is too remarkable 



:a coincidence that the fish normally with but little pigment 



should be when among these weeds bright red, and that the 



fish normally possessing black jsigment should be dark red, 



to permit of a settlement of the question offhand by the easy 



help of the theory of natural selection — without at least some 



further inquiry. 



Possibly the Gulf-weed fauna is an example of something of 



the kind. Prof. Moseley, in his work "Notes by a Naturalist 



■on the Challenger" comments, as have many other writers, 



■upon the extraordinary colour resemblances which exist 



between the animals living upon and among the weed, and 



the weed itself. The Gulf weed is of an olive yellow colour, 



.and " the crabs and shrimps which swarm in the weeds are 



of exactly the same shade of yellow as the weed, and have 



white markings upon their bodies to represent the patches of 



2Iembranipora. The small fish Anteniucrius * is in the same 



* The Antennariua referred to is really Pterojjhrytu histrio — an apt 

 specific name. It is suggested by a writer in Proc. Acad. Nat. Sci. 

 i(Pliiladelphia,1889, p. 344), that the -white patches on the G-ulf- weed animals 

 imitate the shells of a minute worm Spirorhis. The writer also relates 

 that this little fish was first mentioned by Osbeck in 1757, who remarked: 

 " Probably Providence has clothed it in this leaflike manner, in order that 

 the predaceous fishes might confound it with the seaweed, and therefore 

 mot exterminate it." 



