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You may search all the museums and uearly all the books 

 in the world and you will find that scarcely a single instance has 

 heen brought forward, even by way of suggestion, of protective 

 mimicry among mammals. The ore case quoted in Beddard's book 

 on Animal Colouration is that of a tree shrew which inhabits 

 certain of the East Indian Islet*, and which has a very close 

 resemblance to a black squirrel of about the same size, plentiful 

 in the same regions. In the Natural History Museum of South 

 Kensington you will find the two animals mounted side by side, 

 and certainly the resemblance is very close. Moreover, the 

 shrews are an eccentric and versatile race, and would, therefore, 

 be more likely to exhibit protective mimicry than many other 

 families of mammals. It appears pro^lable that this is an 

 instance of aggressive rather than protective mimicry, for 

 squirrels are as a rule vegetarians, and, therefore, their presence 

 would not alarm the insects and other small deer which inhabit 

 the branches when they are constantly passing to and fro. 



Now let us consider for a moment why it is that protective 

 mimicry is not more common among the comparatively highly 

 organised mammalia. There are, I think, three principal reasons. 



One is that the mammalia are comparatively very much more 

 modern than the more lowly organised insect population, and 

 therefore possibly they have not had time to evolve such elaborate 

 artifices to escape from their foes. 



Secondly, that the danger which most mammals have to 

 guard against is of a very different character from that which 

 threatened the butterflies and other insects. The latter are 

 preyed upon almost exclusively by insectivorous birds and 

 reptiles. One might say, indeed, that nearly all the shifts 

 resorted to by lepidopterous mimics are expressly for the sake of 

 deceiving the eyes of birds. Now mammals are probably more 

 preyed upon by their fellow mammals than by any other 

 • 'estructive agent, and these warm-blooded enemies seldom, like 

 the birds, trust to a single sense, namely, that of sight in 

 detecting and securing prey. 



Nearly all the mammalians have an elaborate olfactory 

 apparatus and ears, which not only hear the slightest sound, but, 

 owing to the movable external ear trumpet, worn by nearly all 

 mammals, are able to detect the direction from which it comes. 

 Moreover, generally speaking, mammals are more intelligent than 

 birds or reptiles, and can draw better conclusions from the 

 evidence of their senses. It would be of little use for a hare, 

 escaping from a pack of hounds, to resemble some creature 

 which dogs hold in abhorrence ; nor would a field mouse, whose 



