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good to eat. Such forms are apt to be brightly col- 

 ored so that birds can recognize them before sticking 

 their bills into them. Strangely enough numerous 

 cases are known where edible species when not abund- 

 ant have found safety in assuming the colors and 

 markings of the inedible forms, as is shown by the three 

 butterflies. In a vast number of cases animals escape 

 because of their resemblance to their surroundings. 

 The little green parrot keeps among the green foliage 

 of the trees; the ducks are white beneath so that they 

 cannot be seen by fish below against the white sky, 

 and dark above so that larger birds above cannot see 

 them when looking down into the dark depths of the 

 water. The white Ptarmigan is one of a class of 

 animals that spend their winters in snow-covered 

 areas, during which time they are white, but become 

 ash-colored in summer. Notice the Arctic animals 

 in general that live on the land. The desert grouse, 

 like the horned toad, dresses in a livery of grey. 

 Notice the two crustaceans shown; do you think you 

 could see the big fellow on a gravelly bank ? You 

 have doubtless looked many a time at the large moths 

 shown against the bark without seeing them. These 

 resemblances among insects are the rule rather than 

 the exception, as note the grasshopper. Sometimes 

 this resemblance to particular objects is most striking, 

 as in the case of the little pupa on the twig, or the 



