Permian deposits, [30].
Perna, [402].
Petalopora pulchella, [224], [270].
Petersburgh, Virginia, [97].
------------------, diatomaceous earth at, [97].
Petricola Patagonica, [377].
Petrifactions, nature of, [37].
Petrified forests of conifers, [169].
--------- "horns," [394].
--------- "mushrooms," [242].