Nighthawk, 54, 198, figure 29, p. 36; figure 30, 

 p. 36; figure 73, p. 82; and figure 74, p. 

 82 



"Nuptial dress," erroneous theory of, 4, 5 



Nuthatch, 49, 78, 115, 116 



Nymphalis bolina. See Butterflies 



O 



Obliterative Coloration 



animals which form exceptions to general 

 rule of, 126; combined with background- 

 picturing in birds, 33-71; cooperation of 

 markings with, 30-32 ; erroneous theory of, 

 28; experimental demonstration of, 136; 

 inversion of, 124, 147; law of, 27; per- 

 fection of, in butterflies, 231; principles 

 of, 14-21 ; unaccompanied by obliterative 

 shading, 196 

 See also Counter-Shading and Irides- 

 cence 



Ocellus. See Markings 



Ocelot, 132, 17s 



Old Squaw. See Duck 



Opossum, 119 



Optical illusion, the basis of protective color- 

 ation, 3 



Orang-outan, 122 



Ornithorhynchus paradoxus, 122 



Otter, 119, 130 



Ounce, 13S, 141 



Outline concealment, natural devices for ac- 

 complishment of, in animals, 95 seq., 

 227 



Owl 



American great horned, 41, figure 36, p. 

 41; European eagle, 41; great gfay, 41; 

 lapp, 41; long-eared, figure 37, p. 42, and 

 figure 38, p. 42; short-eared, figure 48, 

 p. 46; screech, 41, 42, 100; snowy, 114, 

 iSi> 152 



Owl Butterfly. See Butterfly, Calligo eury- 

 lochus 



Oyster-catcher, 27, figure 62, p. 78 



Paca. See Lape 



Pangolin, 125 



Pantaloons (leg-feathers). See Appendages 



Papilionidce. See Butterflies 



Parrakeet, 27 



Parrot, 27, 108, 167 



Partridge, 13 



Patterns 



axiom of, 80; obliterative principles of, 

 9, 77-80; background picture, see Back- 

 ground-picturing Patterns 

 Dewdrop 



butterflies, 229, 230; spiders, 210 

 Flight 



of butterflies, 222-224; of moths, 233 



Patterns — ConUnued 



Flower 



of butterflies, 216, 220, 228, figure 128, p. 

 216, figure 129, p. 216; humming-birds, 

 103; spiders, 210 



Hiding 



of butterflies, 216, 217, 219, 225 ; of locusts, 

 199; of moths, 225 



Hole-picturing 



of caterpillars, 195; leopards, 133; owls, 

 iS8;raccoon, is7;sloth, 1 2 5 , sphinx-moth 

 larva, 125; spiders, 211; whip-poor-will, 

 158, figure 131, p. 216 



Leaf vein 



of caterpillars, 185 



Ruptive 



concealing principles of, 77, 78, 79, no; 

 of ant-eaters, 126; bees, 205; beetles, 201 ; 

 butterflies, 228; ducks, 65, 78; gannets, 

 155; grasshoppers, 199; kingffishers, 155; 

 locusts, 198; magpies, 115; moths, 236; 

 nuthatches, 115; ospreys, 155; pelicans, 

 155; plover, 79; prongbucks, 145; quail, 

 79; skunks, 123, 1 5 1 ; tanagers, in; tit- 

 mice, lis; trogons, no, in; wolverines, 

 123 



Secant 



concealing principles of, 77, 78; of am- 

 phibians, 182; ant-eaters, 126; batrachi- 

 ans, 181; ducks, 78; frogs, 78; harnessed 

 antelope, 143; Hymenoptera, 204, 205; 

 koodoo, 142; Livingstone's eland, 142; 

 maekerel, 162; moths, 236, 239; sparrows, 

 78; squirrels, 143; toads, 78; zebras, 138, 



139. 143 

 Variable 



ptarmigans, 45 

 See also Markings 



Peacock 



See Frontispiece; concealing effect of tail 

 of, 9S, and legend of Frontispiece; obliter- 

 ative iridescence of, 88, 244 



Pelican, 155 



Perspective, of animal patterns. See Back- 

 ground-picturing Patterns 



Petrel, 75 



Phalanger, 119 



Pheasants 



concealing effect of tails of, 95, 97, figure 

 133, p. 230; ocelli of, 229 



PierincB. See Butterflies 



Pigmentation in caterpillars, 187 notes 



Pintail. See Duck 



Pipe-fish, 167 



Pipit, 45 



Plaice, 164 



Plant Lice. See Aphides 



Plover, 52, 53, 79, figure SI, p. 48; figure S2, p. 

 48 ; figure 67, p. 81 ; figure 68, p. 81 ; figure 

 70, p. 82; figure 71, p. 82; and figure 72, 

 p. 82 



Polliwog, 169 



258 



