;
amoeboid movements of young, 121-123;
segmentation of, 134, 135.

Owen, on ear of whale, 65;
on natural selection, 333, 334.

Owl, eye of, 75.

P.

Paddle, _see_ Whale, and _Baptanodon discus_.

_Pagurus bernhardus_, 64.

Pain, in relation to the theory of evolution, 417.

Palaeontology, 159-203;
general testimony of, 156-165;
testimony of, in particular cases, 165-203;
consideration of objections to theory of evolution founded on grounds
of, 156-165, and Appendix.

_Palaeotherium_, 190, 191.

Paley, on natural theology, 98, 412.

_Paludina_, successive forms of, 19.

Panama, Isthmus of, 219.

_Panniculus carnosis_, 77.

_Papilio merope_, 330.

Parasites, of animals, devoid of beauty, 408.

Parsimony, law of, 272.

Parthenogenesis, 119.

Partridges, 319.

Peacock, tail of, 378;
courtship of, 383.

Peckham, Mr. and Mrs., on courtship of spiders, 388-390.

Perissodactyls, 182-192.

_Petromyzon marinus_, 148.

_Phenacodus primaevus_, 184, 185.

Phylogeny, _see_ Ontogeny.

Physiological selection, 376.

Pig, embryology of, 153;
feet of, 176, 187;
portraits of wild and domesticated, 312.

Pigeons, portraits of, 298, 299;
feather-footed, 359.

Pilot fish, 289.

_Planorbis_, transmutations of, 200, 201.

Pleasure and pain, in relation to the theory of evolution, 417.

_Plica semilunaris_, 75.

_Pliohippus_, 189.

Polar bear, skeleton of, 174;
feet of, 178.

Polar bodies, 125, 126.

Polar star, 129.

Polyps, 114.

Porpoises, 24, 25, 50.

Poulton, E. B., on warning colours, 325, 326;
on mimicry, 331, 332;
sexual selection, 400, 401, 449, 450.

Poultry, portraits of, 300-302.

Pronucleus, 126-128.

Prophetic types, 272, 351-362.

_Prophysema primordiale_, 140.

Protective colouring, 317-323.

_Protohippus_, 189.

Protozoa, 104.

Ptarmigan, 317, 318.

_Pterodactyl_, wing of, 56.

Purpose, Darwin's use of the word, 281, 340.

Puss moth, larva of, 325, 326.

Python, 66, 67.

Q.

Quadrumana, muscles of, 76, 82, 83;
perforations of humeri of, 94, 95;
hair on phalanges of, 91.

R.

Rabbit, embryology of, 153;
multiplication of, in Australia, 286;
portraits of wild and domesticated breeds of, 308;
protective colouring of, 319, 320.

Radiate form, beauty of, 408, 409.

_Raia radiata_, and _batis_, 367-371.

Rats, species of, restricted to Old and New Worlds, 212;
British and Norwegian, 285, 28