Patagonia and its terraces, [29].
Phenacodus, [185].
Physical evolution of man, [254].
Pithecanthropus, [188].
Planetesimal theory, [155].
Playing dead, [107].
Playing 'possum, [107].
Polygamy in animals, [137].
Pond-snail, development of, [46].
Potato worm, [142].