1901.] EVOLUTION OF PATTERN IN FEATHERS. 325 



stripes ; while the Golden (Plate XX. fig. 7) and Grey Plovers 

 show the most common form of marking, the yellow spot being 

 the ground-colour or what is left of it, between greatly- 

 enlarged and connected bars. Passing over many forms of more 

 or less interest, we may take as our typical example the Knot 

 (Tringa canutus). The young shows on the back a plain grey 

 feather with light border and a dark arrow-shaped edge repre- 

 senting the last bar ; on the breast there is the primitive dark 

 stripe, especially on the throat and chest, and the whole is slightly 

 suffused with pink. In the adult in winter the dark bar on the 

 back has been absorbed, and we have the plain grey self-coloured 

 feather ; while on the breast, which is quite white, the longitudinal 

 dark markings have been replaced by bars of more or less irregular 

 shape. In the summer, the adult has the feathers of the scapulars 

 black with a white edge and with four or more reddish spots, the 

 type of feather being as in that of the Golden Plover ; the breast is 

 entirely suffused with red, having the black markings, where they 

 occur, as in winter, but the majority of the feathers being self- 

 coloured. 



It will be noticed by those who have borne with me so far, 

 that these sequences of plumage offer some difficulty, for if we 

 imagine the young to be the nearest to the archaic type, the winter 

 bird will follow naturally as a higher form ; but then we are 

 met by the fact that although the colours are much brighter, 

 the pattern on the adult in summer is hardly so far evolved as 

 that on either the young or the winter bird. 



This is a difficulty to which I am unable to offer a safisfactory 

 solution. The tendency of young waders to resemble the breeding- 

 plumage of their parents, rather than the duller plumage, has 

 always puzzled me, long before any ideas of pattern entered into 

 my thoughts ; and now we see that the breeding dress represents 

 a lower form of evolution, if my ideas be right, than the non- 

 breeding dress, the reverse of what is usually the case. The only 

 suggestion I can offer is that in the young and breeding dress we 

 have the plumage worn at a time when, food being more plentiful 

 and its breeding-haunts more congenial, there was no need for the 

 bird to undertake such long journeys, and that scarcity of food, 

 causing diminished energy, combined with the necessitv of a more 

 protective colouring from its many new enemies met with in the 

 course of its wanderings, led to the adoption of the grey winter dress. 



The Gnlls and Terns need no con at; in their yomiL, r state 



they all show in various stages the longitudinal stripes, or half- 

 formed bars, showing clearly that their adult plumage lias been 

 subsequently evolved. The spots of Colymbhke are the white 

 interspaces between the very much overgrown bars. 



I have now been roughly through many of the main orders of 

 birds, ami have tried to show that the ideas suggested by the 

 variations in the Sparrow-hawk hold good lor all the groups on 

 which 1 have touched, and, if so, probably for all birds. In Borne 

 cases my reasonings may appear a little Far-fetched, and in others 



