I 2O ZOOLOGY. 



distinguished from its environment because of its color, or 

 form, or both. This resemblance may be to some particular 

 object, or merely a general harmony of color with the sur- 

 roundings. As illustrative of the latter head we may cite the 

 quail among the dead leaves and grasses, the sober-hued lizard 

 on the logs, the green caterpillars or tree-toads among the 

 leaves; the tawny color of desert animals, the white fur of 



FIG. 58. 



FIG. 58. A sea-horse, Phyllopteryx eques. From Eckstein. 



Question on the figure. Compare this figure of sea-horse with figures 

 of other species and note the chief difference between them and the 

 typical fishes in external characteristics. What about the figure suggests 

 protective resemblance? At what point does the tail of the fish end? 



arctic forms, the transparency of many marine animals. In- 

 deed the great majority of animals show some traces of re- 

 semblance to the surroundings, since it is alike advantageous 

 to the predaceous and to their prey. In some instances there is 

 the ability to change color with changing environment, as in 

 the tree-toads, the chameleon, and in some fishes. This is not 

 by the direct action of the light on the pigment cells but by 

 reflex action of the nervous system stimulated through the 

 eyes. 



Many other animals become inconspicuous by reason of a 

 resemblance to special objects. It is among the insects that the 



