272 THE ZOOLOGIST. 



One could go on for page after page giving such instances : 

 Meadow-Lark and Kalkoentje ; Auk and Penguin ; the Common, 

 Golden, and Marsupial Moles (an excellent instance — a century 

 ago they would have gone assuredly into a single genus !) ; 

 Swallows and Swifts ; Gulls and (certain) Petrels ; Diving Ducks 

 and Divers, &c. 



When two species closely resembling one another live side by 

 side, the explanation of "mimicry" has been used. One might 

 legitimately use it in relation to the present subject, and say 

 with truth that the Common Snipe, although structurally not 

 even nearly related, is mimicking the Jack- Snipe. In such cases 

 naturalists have attempted to find some connection between the 

 two parties to a case of "mimicry," yet it should be clear 

 that, even though both are striving towards the same goal, and 

 within a short distance of it, they may still not be in contact in 

 any way. 



I am afraid I have dragged the subject out too far, but really 

 I have not said half that I would have said. The important 

 question of food and feeding habits must be left for a separate 

 paper, as must also be the subject of voice. I have accumulated 

 many observations on other "pairs" of birds — Grey and Golden 

 Plovers, Common and Dusky Eedshanks, Common and Green 

 Sandpipers — and hope to show that" the relationships in these 

 cases are merely superficial, and to show also how the patterns 

 of the plumages have been directly changed under the influences 

 of the habitat that each species has been forced, in the stress of 

 competition, to occupy. One result of this study is that I 

 always doubt the relationship between two organisms, either 

 plants or animals, if they appear very closely allied and occupy 

 the same country ; yet the difficulties of investigating such sets 

 as our three Leaf- Warblers (Phylloscopus), where one must work 

 with, so to speak, a microscope in one hand and a field-glass in 

 the other, are extremely discouraging, in spite of the high 

 interest of the problems they present. 



