Family and Generic Differentiation. 323 



seriously imagine for one moment that tbis particular and 

 constantly occurring colour-pattern was absolutely indis- 

 pensable for the continued existence of this particular race 

 of Plovers as contrasted with other races of Plovers, and 

 from the point of view of an indispensable harmony with 

 their environment, or ever had been so indispensable at any 

 age or under any circumstances ? The mere fact that such 

 a stereotyped pattern is found in such varying types of 

 environment as the peculiar plateau of St. Helena, the 

 grassy velds of southern Africa, or the sandy shores of our 

 own islands, surely suggests that its origin is not entirely a 

 matter of concealing coloration or adaptative. On the con- 

 trary, may we not surmise tliat this particular colour-complex 

 was a character or a colour-tendency which was impressed 

 on these Ringed Plovers ages back, through the influence of 

 some purely fortuitous shuffling of the chromosomes in the 

 germ-cells of some remote ancestor ? It is a colour-pattern 

 or a colour-tendency which has persisted, not because it 

 owed its origin to any formal plan for the protective con- 

 cealment of these Plovers, but because the germ-cell, once 

 started on a certain line, could not help repeating itself in 

 this direction, and because, since the colour-tendency was 

 not harmful to the race, there was no excuse for any elimi- 

 nating factor to suppress either it or the race ; and so the 

 germ-cell, or the jugglery which takes place within it, has 

 gone on repeating itself, and will go on repeating itself, until 

 some sudden mutation or reshuffling of the chromosomes in 

 the germ-cells of any particular individual of any species 

 starts a new line of evolution in colour-pattern (a genetic 

 variation or mutation). 



In such a case, then, as the colour-pattern which is typical 

 of the cosmopolitan Hinged Plovers, I submit that we have 

 a colour-complex which is endogenous or genetic. It is 

 congenital. It can be used as a generic test or character. 

 But, of course, we have got to be on our guard in making 

 use of colour-characters in classification; for just as in the 

 case of deeper structural features we have to eliminate the 

 homoplastic factor in cases of mere convergent likenesses, 



