INDEX 



567 



Devonian, 399 ; Eocene, 501 ; Jurassic, 

 462; Mesozoic, 441 ; Miocene, 515; 

 Oligocene, 508; Ordovician, 379; 

 Palaeozoic, 367 ; Permian, 432, 437 ; 

 Pleistocene, 537 ; Pliocene, 521 ; Silu- 

 rian, 389; Triassic, 448. 



Plateau, Pourtales, 173. 



Plateaus of Arizona, 316 ; of Utah, 316. 



Platinum, 266. 



Platte River, 322. 



Platyceras, 419*, 425. 



Platycrinus, 400, 424. 



Platyostoma, 392*, 393. 



Platystrophia, 382. 



Pleistocene epoch, 355, 525!, 529. 



Plesiosauria, 454, 470, 490, 495. 



Plesiosaurus, 470*. 



Pleuracanthus, 426, 434*. 



Pleurotomaria, 382, 423*, 425, 466. 



Pliauchenia, 517. 



Plication, 240. 



Pliocene epoch, 355, 496, 5i8f. 



Pliosaurus, 470. 



Plutonic rocks, i89f, 277^ 



Po, delta of, 142. 



Pocket gophers, fossil, 509. 



Pocono stage, 409, 410. 



Poebrotheriitm, 509. 



Polymastodon, 505. 



Polysynthetic twinning, 14. 



Pompeii, 38, 51, 52*. 



Ponderosa Marls, 475. 



Popanoceras, 434. 



Poplars, fossil, 486, 502, 515, 516. 



Populus, 485. 



Porcelain clay, 207. 



Porphyritic texture, 47, 190! , 196. 



Portage stage, 394. 



Portheus, 490. 



Pot holes, 86, 330. 



Potomac River, 324, 327, 328 ; series, 

 474t, 475- 



Potsdam epoch, 355, 368. 



Potter's clay, 207. 



Pourtales plateau, 173. 



Pre-Cambrian ores, 364; periods, 356; 

 rocks, 364. 



Precipitates, chemical, 208. 



Prehistoric time, 356. 



Prestwich, Sir J., 59. 



Primary rocks, 495. 



Prisms, 9*, 10*. 



Procamelus, 517. 



Pro duct idee, 391, 434. 



Produchis, 402, 419*, 423* 425, 451. 



Proetus, 391, 424. 



Proganosauria, 435. 



Protapirus, 509. 



Proterosaurus, 435. 



Protoceras, 509. 



Protohlppus, 517. 



Protoreodon, 506. 



Pseudodiadetna, 487, 489*. 



Pseudomorphs, fossil, 346; mineral, 13. 



Pteraspis, 403. 



Pterichthys, 404*. 



Pterinea, 401*, 402. 



Pterodon, 508. 



Pterophyllum, 449. 



Pteropod ooze, 178, 179*. 



Pteropoda, 374, 393. 



Pterosauria, 47 if, 491, 495. 



Pterygotus, 391, 402. 



Ptilodus, 493, 505. 



Ptyc kites, 434. 



Ptychoceras, 489* 490. 



Ptyonius, 427. 



Purbeck stage, 493. 



Puerco stage, 496, 498, 505. 



Pumice, 197. 



Pumiceous texture, 189. 



Purpurina, 466. 



Pyramid, 10*. 



Pyramid Lake, 151. 



Pyramidal system of crystals, 9. 



Pyrenees, 515. 



Pyrite, 25 ; auriferous, 266 ; deposition of, 



130. 

 Pyroclastic products, 277 ; rocks, 203. 

 Pyrotherium beds, 523. 

 Pyroxene, i9t, 193, 194, 199, 202, 289; 



andesite, 200. 

 Pyroxenite, 202. 

 Pythonomorpha, 490, 495. 



Quail, fossil, 503. 



Quartz, I5f, 193, 194, 196, 198, 201, 266, 

 289, 291, 296, 358; deposition of, 130; 

 conglomerate, 207; diorite, 200; por- 

 phyry, I98f, 279 ; schist, 297 ; smoky, 

 15 ; trachyte, 198. 



Quartzite, 289, 293^ 



