Pachysporangium, 682 
Pachytheca, 682 
Pacific Ocean, depth of, 32; drifted pumice 
of, 436; volcanoes of, 253, 204, 259 ; 
subsidence of floor of, 467 
Pack-ice, 111 
Palzarea, 651*, 665, 667*, 669* 
 Palzxaster, 664 
Palzasterina, 650, 651*, 664 
Palechinus, 676 
Paledaphus, 699 
Palzxocaris, 724 
Palzocastor, 869 
Palzocherus, 856 
Palzxocoma, 664 
Palzocorystes, 819 
Palzocrangon, 724 
Palzodiscus, 680 
Paleogene, or older Tertiary, 836 
Paleolithic deposits, 903 
Palxomeryx, 866 
Palzonictis, 840 
Palexoniscus, 753* 
Palxontina, 775 
Paleontology, nature of, 603 
Palzonycteris, 856 
_ Palzophis, 846 
Palzophycus, 658, 662 
Palzopteris, 700, 706, 708, 726 
Palzopyge, 654 
Palzoreas, 879 
Palzxoryx, 879 
Palxosaurus, 763 
Palzxosiren, 754 
Palzotherium, 840, 842*, 856; as a type- 
fossil, 616 
Palezotragus, 879 
Palzozamia, 786 
Palzozoic rocks, 647 
Paleryx, 857 
Palagonite tuff, 165, 547, 740 
Palaplotherium, 840 
Paleschara, 665 
Palms, fossil, 804, 838, 855, 866 
Paludina, 796, 817, 845, 874, 897 
Panama, recent submergence of Isthmus 
of, 283 
Pandanus, 803, 839 
Paniselien (Systeme), 849 
Panopza, 818, 856, 862, 863*, 874, 895 
Paracyathus, 850 
Paradozides, 649%, 650, 657, 659 
Paradoxides Beds, 652, 658 
- Paragonite, 74 
Paragonite schist, 124 
Parahyus, 842 
Parallel roads, 892 
Parasmilia, 804 
Parexus, 714 
Paris basin, 847, 858 
Park Mountains, Colorado, 915 
Parkia, 714 
Parrotia, 877 
Passes between valleys, 38; origin of, 926 
INDEX. 
fe I I 
959 
Patella, 792 
Pearlstone, 141 
Peat, 170 
mosses or bogs, formation of, 321, 458 ; 
rate of growth of, 460 ; bursting of, 460 ; 
blue-iron earth of, 84; antiseptic power 
of, 460; burial of organisms in, 605; 
succession of in Denmark, 909 
Pebbly structure, 87 
Pebidian rocks, 643 
Pecopteris, 726, 752, 771*, 853 
Pecten, 753, 762, 766*, 774, 806, 847, 855, 
862, 873, 895* 
Pectunculus, 847, 860, 862, 863*, 873, 881 
Pegmatite, 132; veins of, 552, 557, 641 
Pegmatoid structure, 131 
Pelites, 160 
Pelitic structure, 88 
Peltastes, 820 
Peltocaris, 664 
Penarth Beds (Rheetic), 764 
Pennant Grit, 744 
Pennine chain, 738 
Pennsylvania, fire-wells of, 236; oil regions 
of, 351; coalfield of, 306 
Pentacrinus, 773, 774*, 818 
Pentalophodon, 880 
Pentamerus, 665, 675*, 696 
Pentamerus Beds, 670 
— Limestone, 675 
Pentremites, 722 
Peperino, 165 
Perched blocks, 154, 411 
Peribos, 880 
Peridotites, 78, 151 
Periechocrinus, 678 
Perimorphs, 61 
Perlite, 141 
Perlitic structure, 89 
Permeability of rocks, 299, 346; affects 
the discharge of rivers, 359, 361 
Permian System, 750 
Permo-carboniferous, 750 
Perna, 795, 806, 866 
Persaonia, 862 
Persea, 862 
Pervious, defined, 344 
Petalodus, 724 
Petherwin Beds, 700 
Petrification, most important media of, 352, 
610; indicative of the alteration of rocks 
by infiltrating water, 352; lime as the 
agent in, 83; silica as the agent in, 66; 
iron disulphide as the agent in, 86 
Petroleum, 172 ; in springs, 351 ; associated 
with eruptive rocks, 576 
Petrosiliceous structure, 131 
Peuce, 786 
Phacops, 664, 677*, 697* 
Phaneropleuron, 710 
Phascolomys, 881 
Phascolotherium, 
Phaseanus, 879 
Phasianella, 819 



783, 784* 
