PROCEEDINGS, 1915. 79 



ject will appear darker below than above, owing to the fact that the source 

 of light is usually above, and it is this fact that helps us to detect the 

 presence of a solid body even when placed before a background of the 

 same color. And so we will readily see if this under shadow effect is 

 counteracted by the under parts being lighter color 3d, that the animal 

 so colored will be less likely to be seen. 



The second principle we notice is, that the back is mottled with greys, 

 browns, and black, and that these are precisely the colors of the forest 

 floor, the dead leaves, mud, dead twigs and innumerable other brown, 

 grey and black things which cover the ground on which the bird settles, 

 and lives. And the bird knows perfectly well how well its coat blends into 

 its surroundings, for it will remain motionless depending upon its pro- 

 tective coloring until almost trodden upon. 



We have become so used to this resemblance of creatures to their 

 natural surroundings, that we seldom think of it as anything wonderful. 

 It is likely that it is only an accident that the tiger living among the tall 

 yellow jungle grasses has its body marked with black and yellow stripes, 

 that the leopard living in the checkered lights and shadows of the forest, 

 has its body marked with leaf shadows, that the lions tawny brown 

 coat blends so well into the yellow sands and rocks of the desert? How 

 closely the nocturnal moths resemble the bark of the trees on which they 

 rest, only those who have hunted for them in these positions know. 



The cases we have touched upon thus far, have all been examples of 

 general resemblance, i.e. their coloring resembled their general surround- 

 ings. I will now mention one or two cases of special resemblance. In 

 these the form of the animal usually assists the coloring in making the de- 

 ception perfect. 



I will take the liberty to use one more example outside the insect 

 class. Along our coasts when the tide goes out, there are left among the 

 rocks, little pools that are veritable fairy worlds of wonder. Covering 

 many of the rocks in these pools are finely branched sea-weeds, and living 

 among them is a strange little creature, (shown here much enlarged) which 

 is called a "sea-slug" and which bears along its back strange branched- 

 processes, so that the creature seems to be merely a part of the weed 

 covered rock upon which it rests. 



Here is an insect which is more often heard than seen — the katydid. 

 It is drawn here in resting position and you will notice that not only do 

 the folded wings resemble in general outline and coloring a narrow leaf, 

 but that the veiny framework of the wings is so arranged as to resemble 

 the veining of a leaf. 



A near relative of the Katydids is our common brown locust, found 

 on hot dusty roads. After crackling along in front of us he comes to rest 

 a perfect sliver of stone. 



