Family and Generic Differentiation. 331 



possibly conceive that the presence of this white wing- 

 spot in the one case, or its absence in the other, could 

 serve any useful purpose, or the reverse ? Could anyone 

 possibly imagine that the white wing-spot had been directly 

 impressed on the white wing-spotted race through the agency 

 of external factors represented by a difference of environ- 

 ment ? The idea is absolutely unthinkable; and the sooner 

 we cease to practise any sort of self-deception in this direc- 

 tion the better. On the contrary, what this story of the 

 genus Cipreba, thus briefly condensed, seems to prove is 

 that colour-pattern is a deep-lying phenomenon, an affair 

 of the germ-cell — a congenital manifestation. It owes its 

 continued manifestation after its first inception to the effects 

 of isolation and segregation. As such it cannot be the 

 superficial and contemptible factor which it has been held 

 to be. 



I may add that the presence of the white wing-spot in the 

 race inhabiting the green-coloured area is invariably con- 

 stant, whether species possessing such a spot live at an 

 altitude of 8000 or 9000 feet in the Peruvian Andes, or 

 whether they are found in arid and sparsely vegetated 

 country at dead sea-level, such, for instance, as is found in 

 the very isolated Cayman Islands. In all these species 

 mere depth of tone in coloration is very variable, as we 

 might expect — the fundamental colour-pattern is constant. 



To further accentuate the moral of this tale, I have here 

 two pairs of nestling Plovers or Waders. In the one pair 

 you see a nestling Stone-Curlew from our own islands 

 (Burhinus wdicnemus) and another from Australia (^Burhinus 

 magnirostris) ; in the other pair a nestling Oyster-catcher 

 (^Hamatopus ostralegus), again from our islands, and another 

 nestling (H. palliatus) from America. In either pair the 

 same identical details of colour-pattern are stereotyped with 

 almost, mechanical precision ; and we are asked to believe 

 that this precise identity of detail has been stamped upon 

 each particular pair of nestling Plovers by a corresponding 

 precision of identity in the immediate environment repre- 

 senting the respective " birth-places " of either of these two 



z2 



