LIST OF ILLUSTRATIONS xiii 



FACING PAGE 



Prairie-dog on edge of its burrow, in the Washington National 



Zoo .... . . . . ' 80 



A pair of pronghorn antelopes photographed in the Washing- 

 ton National Zoo 80 



Tree-toad. . - . ...... . . . . .' . . 84 



Tree-toad. An excellent example of protective marking . . 84 



Bullfrog resting at surface of water 86 



Bullfrog standing half submerged in water 86 



Garter-snake 88 



Snapping-turtles fighting 88 



Moth unfolding its wings after leaving cocoon 90 



Yellow angel-fish. Showing its natural surroundings . . .104 



Moonfish 1 06 



Garfish . . . > . . 1 08 



Bluefish. Being a surface-fish, no accessories are necessary . no 



Squirrel-fish. This is a bright red fish, and the photograph 



illustrates the advantage of the isochromatic plate . . . 112 



Skunk-cabbage, leaf unfolding. April 19, 1901 114 



Skunk-cabbage, leaves nearly open. April 19, 1901 . . .114 



Violets (Viola bicolor) 116 



Pink hepatica. April 23, 1901 118 



Bloodroot and hepatica. April 19, 1901 .120 



Fringed gentian 122 



Jack-in-pulpit. May 1 8, 1901 124 



