960 
Phemphigaspis, 660 
Phillipsastrea, 722 
Phillipsia, 724 
Phlebopteris, 771* 
Phoca, 875 
Phenicites, 855, 862 
Pholadomya, 774, 844, 873 
Pholas, 818, 865 
Pholiderpeton, 733 
Pholidophorus, 763, 775 
Pholidosaurus, 808 
Phonolite, 139 
Phosphates, 84 
Phosphatic coucretions, 488; deposits, 168, 
470 
Phosphorite, 84 
Phragmoceras, 666, 679* 
Phtanite, 719, 738, 743 
Phyllite, 121 
Phylloceras, 763, 784, 789* 
Phyllodus, 840 
Phyllograptus, 663* 
Phyllopods, 651, 664, 724 
Physa, 796, 848 
Physiographical geology, 910 
Pickwell Down Group, 699 
Pikermi, mammalian fauna of, 865, 878 
Pikrite, 151 
Piloceras, 668 
Pilton Group, 699 
Pinacoceras, 763 
Pines, early forms of, 868, 871 
Pinites, 730, 772, 786, 859 
Pinna, 750, 774, 819, 847 
Pinus, 846 
Pipe-clay, 160 
Pisania, 857 
Pisidium, 875 
Pisodus, 844 
Pisolite, 113 
Pisolitic Limestone of Paris basin, 827 
Pitchstone, 140 
Pitharella, 845 
Placoparia, 667 
Plagiaulax, 783, 785* 
Plagioclase, 71, 142 
— augite rocks, 146 
— rocks, 130 
Plains, characters of, 40; origin of, 928; 
formed by the sea, 449; of marine de- 
nudation, 451 
Plaisancian (Pliocene), 878 
Plane-tree, fossil forms of, 804, 839, 868, 
871 
Planer (Unter-, Mittcl-, Ober-), 822 
Planera, 866 
Planets, relative densities of the, 7; com- 
position of, 9 
Planorbis, 796, 855*, 866, 875 
Plants, destructive action of, 452 ; conserva- 
tive action of, 456; precipitation of 
caleium carbonate by, 354; reproductive 
action of, 457; chemical action of, 461 ; 
terrestrial, of minor value for strati- 




~ENDEX. 
graphical purposes, 611, 733; chances 
against the preservation of the remains 
of terrestrial, 611; evolution of, 619, 
625, 626, 833 ; relation of to theories of 
development, 625: oldest known terres- 
trial, 662 
Plastic clay, 844 c 
Plateaux, types of, 40 
Platemys, 807, 846 
Platycrinus, 722 
Platyschisma, 666 
Platysomus, 753* 
Plectrodus, 666 
Pleistocene, definition of, 836; described, 
883 
Pleochroism, 190; examples of, 74, 76, 77, 
79, 80 
Plesiarctomys, 856 
Plesictis, 856 
Plesiosaurus, 767, 777, 781*, 809; as type- 
fossil, 615 
Plesiosores, 856 
Pleuracanthus, 732 
Pleurocystites, 664 
Pleurodictyum, 696 
Pleuromya, 789 
Pleuroneura, 754 
Pleurorhynchus, 688 
Pleurotoma, 840, 855 
Pleurotomaria, 666, 697, 723, 724*, 753, 
795, 806 
Plication of rocks, 53 ; a consequence of sub- 
sidence, 314; connection of with cleay- 
age, 311; connection of with metamor- 
phism, 308, 579, 582, 584 
Plicatula, 818 
Pliocene, 870 
—, definition of, 836 
Pliohippus, 881 
Pliolophus, 840 
Pliopithecus, 864 
Pliosaurus, 778 
Plocoscyphia, 815 
Plum, fossil species of, 871 
Plutonia, 649*, 651 
Plutonic defined, 134 
—— action, 198 
eruptive rocks, 535, 538 
Plutonists and Neptunists, 298 
Po, area of basin of, 444 ; sediment in water 
of, 370; annual discharge of sediment, 
444; heightening of plain of, 382; delta — 
of, 390 
Poacites, 849 
Podogonium, 862, 877 
Podozamites, 761, 772, 828 
Poebrotherium, 869 
Poikilitic, 750 
Polar flattening, an argument for original 
plasticity of the earth, 12 
Polarization, analysis by, 188 ; examples © 
of, 66,.71, 78, 74, 76, 77, 79, 80, 81; 
aggregate, 8l 
Pollicipes, 819 


