490 



INDEX 



Pelagic auimals, colours of, 193 | 



Phasmidfe, resemblance of, to sticks 



and leaves, 203 

 Physiological selection, 180 

 Pickard-Cambridge, Rev. 0., on sexual 



selection, 296 (note) 

 Pieridffi, sexiial diversity among, 271 

 Pigeons, varieties of, 89 



domestic, derived from wild 



rock-pigeons, 90 

 curious coiTelations in, 140 

 ■white eggs of, protective, 213 

 Pigs, great increase of, in South 

 America and New Zealand, 

 28 

 Pikermi, extinct animals of, 377 

 Pipits as illustrating divergence, 108 

 Planorbidfe, variations of, 44 

 Plants, the enemies of, 16 

 variability of, 76 

 constitutional variation of, 94 

 colour relations of, 302 

 true mimicry rare in, 303 

 exotic rarely naturalised in 



Europe, 356 

 dispersal of, 361 

 northern, in southern hemi- 

 sphere, 368 

 identical on summits of remote 



mountains, 369 

 progressive development of, 397 

 geological development of (dia- 

 gram), 402 

 Plovers, recognition marks of 



(figure), 221 

 Plumes, origin of accessoi-y, 291 



muscular relation of ornamental, 

 292 

 Poisonous fruits, 307 

 Porto Santo, rabbits of, 326 

 Poulton, Mr. E. B., on variable colours 

 of larvae and pupae, 196, 198 

 on concealments of insects by 

 resemblance to environment, 

 202 

 on protective form of Noto- 



donta ziczac, 210 

 on inedibility of conspicuous 

 larvae, 237 

 Pouters, 90 

 Primulaceae, variations of structure in, 



79 

 Problem, the, before Darwin, 6 



Problems in variation and heredity,410 

 Procression in plants and animals, 



395 

 Protection by terrifying enemies, 209 

 Protective colouring, variable, 195 

 of white-headed fruit - pigeon, 



200 

 of African sun-birds, 200 

 of Kerivoula picta, 201 

 of sloths, 201 



of larva of Sphinx ligustri, 202 

 of stick and leaf insects, 203 

 of caterpillars, 203, 205 

 of butterflies, 206 

 Ptilopus cinctus, protective colour of, 



200 

 Pugnacity of birds with accessory 

 plumes, 294 



R 



Rabbit, use of white tail of, 218 



Rapid increase of plants, 28 

 Raspail, M., on variability in a grass, 



80 

 Rat, black, spread, of, 34 

 Rattlesrake, use of rattle of, 262 

 Raven, why black in arctic regions, 



191 

 Reciprocal crosses, 155 

 Recognition marks of herbivora, 218 

 of birds, 222 



of tropical forest birds, 224 

 of insects, 226 

 Reproductive functions, susceptibility 



of, 153 

 ReptUes, geological distribution of, 406 

 Rhinoceroses, evidence of evolution 



afforded by fossil, 383 

 Rocks, all stratified formed in shallow 



water, 344 

 Rocky Mountains, scarcity of mono- 



cotj'ledous in, 401 

 Rodents, prevent woody vegetation in 



the pampas, 23 

 Romanes, Professor G. J. , on useless 



characters, 131, 139 

 on meaningless peculiarities of 



structure, 140 

 on supposed absence of simul- 

 taneous variations, 142 

 on physiological selection, 180 



