380 THE ZOOLOGIST. 



perfect mimicry. May it not therefore be that we have, in this 

 group of brown Orioles, the original type of the family, un- 

 differentiated ? As they spread east and south we may trace the 

 gradation, through the brown striation of the New Guinea bird, 

 to the brighter, green-tinged form of the West Australian and 

 the green plumage of the Southern Australian, while westward 

 the brilliant yellows of the numerous Indian and African species 

 were developed, and another group, preferring higher elevations, 

 passing through the mountain ranges of Java, Sumatra, and 

 Borneo, intensified the aboriginal brown into black, and hence 

 were evolved the deep reds of the various species which culminate 

 in the crimson of Formosa, Oriolus ardens, and the still deeper 

 crimsons of 0. trailli of the Himalayas. 



It is possible that there may be similarity without mimicry, 

 and, by the five laws of mimicry as laid down by Wallace, very 

 many suggested cases must be eliminated. We all know that it 

 is quite possible to find between species of very different genera 

 extraordinary similarity which is not mimetic. Take, for instance, 

 the remarkable identity of coloration in the case of some of the 

 African species Macronyx and the American Sturnella, or, again, 

 of some of the African Campephagce and the American Agelceus. 

 The outward resemblance occurs in both cases in the red as well 

 as in the yellow-coloured species of all four groups. But we find 

 that the Macronyx of America and the Campephagce of Africa, 

 in acquiring this coloration, have departed widely from the 

 plain colour found in their immediate relatives. If we applied 

 Mr. Scudder's theory on insects, we must imagine that the proto- 

 type form has become extinct, while the mimicker has established 

 its position. This is an hypothesis which it is easier to suggest 

 than either to prove or disprove. Similar cases may frequently 

 be found in Botany. The strawberry is not indigenous in Japan, 

 but in the mountains there I found a Potentilla in fruit which 

 actually mimicked the Alpine strawberry in the minutest par- 

 ticulars, in its runners, its blossoms, and fruit ; but the fruit was 

 simply dry pith, supporting the seeds and retaining its colour 

 without shrinking, or falling from the stalk for weeks — a 

 remarkable case, we cannot say of unconscious mimicry, but 

 of unconscious resemblance. Mimicry in birds is comparatively 

 rare, and still rarer in mammals, which is not surprising when 

 we consider how small is the total number of the Mammalia, and 



