SEA-HORSES. 179 



the other hand, the leaf-insects, or " walking leaves," of 

 India, both in colour and form, so exactly simulate green 

 leaves that they may be passed dozens of times without 

 attracting attention. All the legs of these curious 

 creatures are furnished with irregular flat expansions 

 looking precisely like bitten leaves ; while the head and 

 fore part of the body forms a kind of stalk expanding 

 behind into a broad and flattened abdomen, covered by 

 the horny wings, which are veined and netted so as to 

 form an almost exact imitation of a leaf. 



We might cite many other instances of inanimate 

 mimicry among insects, but we must pass on to show that 

 this phenomenon is by no means confined to this group of 

 animals. Perhaps we should scarcely expect to find this 

 kind of mimicry in such a comparatively highly organized 

 a creature as a fish ; yet there is a group of fishes, familiar 

 to those who have kept aquaria, under the name of sea- 

 horses, in which it is exhibited in its full perfection. The 

 ordinary sea-horse attaches itself to a sea-weed or some 

 other object by curling its tail tightly round it ; and all 

 these fishes have the habit of anchoring themselves by 

 their tails in some way or another. In all of them the 

 hard, horny body is furnished with a number of prominent 

 ridges and spines ; but in one, belonging to a peculiar 

 group from the Australian seas, these spines attain an 

 enormous development, many of them being prolonged 

 into irregular filaments or streamers of skin, which are 

 especially developed throughout the long and slender tail. 

 As these streamers float in the water, they so exactly 

 resemble, both in colour and shape, the particular kind of 

 sea- weed to which these fishes are in the habit of attach- 

 ing themselves, that the whole creature seems but part and 

 parcel of the fucus ; so that when on the sea-bottom it 

 must be impossible for any carnivorous rover to distinguish 

 between the animal and the vegetable. 



One more instance of this kind of mimicry, and we must 

 close this portion of our subject. This example is taken 

 from the mammalian, or highest class of animals, and, 

 although not such a perfect imitation of form as those we 

 have already mentioned, is very remarkable as occurring 



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