COLOXTR CHANGES IN CORNISH STOATS. 105 



Some suggest this colour change has to do with mimicry. 

 In biology this term has a pretty definite meaning, it was first 

 used by the late Mr. W. H. Bates, and is the term given to the 

 "advantageous resemblance (usually protective) which one species 

 of animal or plant often shews to another." Mimicry is rather 

 the adoption amongst animals and plants of deceptive resem- 

 blances. In the Weasel family the resemblance is not to living 

 forms but to the ground, and this is usual with the higher 

 animals, their colours generally matching their surroundings. 

 Mimicry, though almost unknown amongst mammals, is common 

 with birds and insects. An interesting case given by Mr. A. E. 

 Wallace will perhaps make this difference clearer. In the Malay 

 region he came across an insectivorous mammal ( Cladohates) 

 which closely resembled (mimicked) a squirrel in colour and 

 bushiness of tail, but fed on young birds and insects, and not on 

 fruit. The colour changes in the Stoats are in all probability 

 secretive and not protective, as these animals can take care of 

 themselves. The ordinary dress of the stoat is bicolored, white 

 beneath, which never changes, and is hidden as the animal runs, 

 and a visible dorsal brown which, as we have instanced above, 

 may alter in tint. 



I have seen several times, in the field, the use of the light 

 coloured strip beneath the body of the Weasel family. I 

 remember once when walking over Middleham Moor, Yorkshire, 

 seeing two of these animals, which were crossing a ridge of 

 ground and coming towards me. Suspecting danger they raised 

 themselves on their hinder quarters until they stood full height, 

 the white ventral strip, now fully visible, blended with the 

 sky glare behind them which I was facing, and gave to each 

 stoat the appearance of two narrow dark lines, totally unlike 

 any living animal. 



The following facts point to the variations in colour depend- 

 ing on coldness and snow : in our ordinary Cornish winters these 

 vermiform mammals do not change their colour ; the stoat caught 

 in the blizzard was white ; the specimen sent soon afterwards, 

 when the weather was warmer and no snow upon the ground 

 was again brown, as was a small example of a weasel sent a 

 little later hj Mr. Richards, the game-keeper at Killiow. 



