2IO 



INDEX 



Psilura monacha, PI. 56. 



Psyche unicolor, PL $6. 



Ptarmigan, seasonal color change, i2i,P/. 57. 



Pterodactylus spectabilis, PL 45. 



Pterogon proserpina, PL ?O. 



Pterophryne histrio, 124, 126, PL 6$. 



Public opinion, a part of man's environ- 

 ment, 172, 179. 



Pupa, color adaptation, 121, PI. 59; Logoa, 

 123, PL 63; protective color, PL 56. 



Putorius ermineus, PI. 67. 



Quail, protective color, 118, PL 49. 



Rabbit, confusing coloration, 148; em- 

 bryos, PL 38; illustration of mutation, 

 19; illustration of natural selection, 15; 

 protective coloration not explicable by 

 the inheritance of effects of use and dis- 

 use, 75 ; signal, white rump patch, 146. 



Radiolaria, skeletons, PL 21. 



Recognition marks, 146-147. 



Regeneration and inheritance of parental 

 modification, 71. 



Relationship, key to classification, 91. 



"Relations concerning Ireland" (Giraldus), 



3- 



Religion, a cause of segregation, 169. 



Reproduction, among unicellular organ- 

 isms, 68, 69 ; and length of life, 20, 22, 

 23, 24; asexual, and inheritance 1 of 

 parental modifications, 71; birth-rate, 

 n, 12; easily disturbed, 66; effects of 

 destroying 'organs of, 34; evolution 

 centres in, 82 ; germ cells in higher 

 organisms, 6g; increase in, aids in 

 struggle 'for existence, 17; organs of, 

 in flowering plants, 752, 153, PL 86; 

 regeneration of organs, 71. 



Ring-necked plover, recognition marks, 

 PL 82. 



Robin, illustration of species, 88; rate of 

 increase, n; sexual coloration, 150. 



Robinson, Louis, PI. 100. 



Rock-rose, 152. 



Rocky Mountains, cause of segregation, 61. 



Romanes, G. J., 17,94, 105, 197, 199, PI. 17, 

 PI. 36-38, PI. 43, PI. 44, PL 75, PI- 

 93-99; sexual selection in birds, 53; 

 physiological selection, 66. 



Rosaces, go. 



Rostellum of orchid, 156, PL 89. 



Roux, "Wilhelm, 192. 



Royal Society of London, goose barnacle, 5. 



Ruffed grouse, PL 23. 

 "Ruth," 176. 



Sacculina, 184, 7#5, PL 101. 



Sacrum, human, with tail muscles, PL 95; 



of man and apes, 164, PL 91. 

 Saitis pulex, PL 28. 

 Salamander, embryos, PL 38; tadpole, 



98; warning color, 133. 

 Salamandra maculosa, 133. 

 Salvia, 157; glutinosa, PL 88. 

 Sand-flounder, PL 48. 

 Sandpiper, protective color, 119. 

 Sargassum fish, 124, 126, PL 65. 

 Savage, illustration of social progress, 1 73 



et seq. 



Savoy cabbage, PL 6 y PL 8. 

 Sceloporus undulatus, PL 52. 

 Scepastus pachyrhynchoides, PL 73. 

 Schistocerca, 62. 

 Sclater, mimicry of leaf-cutting ants, 137, 



145, PI- 75- 



Sea-horse, 124. 



Sea-lion, nictitating membrane, PL 36. 



Seasonal change of color, 121, 126, I2Q, 

 PL 57, PL 67. 



Secondary sexual characters, see Sexual 

 selection ; more developed in female, 58. 



Seeds, spiny, not evolved through inherit- 

 ance of the effects of use, 76. 



Segregation, 60-67, J 68; see also 42-47, 48. 



Selection, artificial, 28-31; germinal, 96; 

 natural, 3-47; organic, 27, 28, 177, 192; 

 physiological, 66; "selection value," 17, 



37; 



Selenia tetralunaria, 122. 

 Sesia culiciformis and tipulijormis, PL JO. 

 Seventeen-year^ cicada, 51, PL 29. 

 Sexual coloration, 149-151. 

 Sexual selection, Intro, xi, 47-60, 168, 169, 



!7 2 *73> i7S 178, i79-i 8 3; a cause 

 of segregation, 44; objections to, 56-60. 



Sheep, Ancon, segregation, 65 ; Faroe 

 Islands, segregation, 65 ; merinos and 

 heath sheep do not interbreed, 48; 

 protective color of wild, 120. 



Shore birds, protective color, 119. 



Siberia, former warm climate, 62. 



Signals and recognition marks, 146-147. 



Silurian fossils, 106. 



Simiida-, 164. 



Simplification ("degeneration"), 183-187. 



Siphonophores, transparency, 117. 



Sitana minor , PL 34. 



