Family and Generic Differentiation. 325 



one or two other aspects of the subject of coloration by way 

 of still further clearing the ground, in the direction of trying 

 to show that colour-pattern in the great majority of cases is 

 endogenous or genetic in origin, and so enhancing its value 

 as a character to be used in classification. 



All sorts of pretty theories have been brought forward 

 in connection with this aspect of the coloration of birds; 

 but it seems to me that if concealing coloration was really 

 such a universal phenomenon as it is often made out to 

 be, we ought to find, as a general rule, that there was a 

 far greater, a more universal, and a more intimate com- 

 mingling of every kind of procryptic colour, irrespective of 

 well-differentiated groups of birds *. Instead of this, we find 

 that certain distinctive colour-schemes are characteristic and 

 proper to certain families or genera of birds, quite irrespective 

 of the fact that such families or genera are exposed to 

 precisely similar environments. To be as brief as possible, 

 one gets the impression, in trying to analyse the colour- 

 factors characteristic of families or genera, that in such 

 groups of birds the ancestral germ-cells had, so to speak, 

 two or three colour-factors to " play with " and make the 

 best of. All the germ-cell or the chromosomes could do 

 was to produce variations with the particular colour-factors 

 they had originally at their disposal. If these variations 

 were not flagrantly inharmonious with their environment, all 

 was well and good. 



The accompanying diagram may serve to demonstrate 

 at a glance the idea which I wish to advance. It has 

 reference to the family Drepanididse of the Hawaiian 

 Islands, and, assuming with Dr. Starr Jordan f that Oreo- 

 imjstes bairdi (with its least specialised bill, its wider 

 adaptative powers, its more ubiquitous distribution, and 

 its neutral coloration as regards both sexes) is the most 



* The colour-pattern of nestling Grebes and Moorhens is conspicu- 

 ously different, although their environment is identical ; and many other 

 examples might be given both in the case of nestlings and adults. 



t Cf. 'Science,' vol. xxii. 1905, p. 555. In this article Dr. Starr 

 Jordan assumes this for another reason. 



