(c) The cavities left by fossils which have decayed may be filled with clay, sand, or other foreign matter, and this, becoming subsequently hardened into stone, may constitute a cast of the fossils. Trunks of trees, roots, &c., are often preserved in this way, appearing as stony casts, often with the outer bark of the plant forming a carbonaceous coating on their surfaces. In connection with this state may be mentioned that in which, the wood having decayed, an entire trunk has been flattened so as to appear merely as a compressed film of bark, yet retaining its markings; and that in which the whole of the vegetable matter having been removed, a mere impression of the form remains.
Fossils preserved in either of the modes, (a) or (b), usually show more or less of their minute structures under the microscope. These may be observed:—(1) By breaking off small splinters or flakes and examining them, either as opaque or as transparent objects. (2) By treating the material with acids, so as to dissolve out the mineral matters, or portions of them. This method is especially applicable to fossil woods mineralised with calcite or pyrite. (3) By grinding thin sections. These are first polished on one face on a coarse stone or emery hone, and then on a fine hone, then attached by the polished face to glass slips with a transparent cement or Canada balsam, and ground on the opposite face until they become so thin as to be translucent. In most cities there are lapidaries who prepare slices of this kind; but the amateur can readily acquire the art by a little practice, and the necessary appliances can be obtained through dealers in minerals or in microscopic materials. Very convenient cutting and polishing machines, some of them quite small and portable, are now made for the use of amateurs. In the case of exogenous woods, three sections are necessary to exhibit the whole of the structures. One of these should be transverse and two longitudinal, the latter in radial and tangential planes.
IV.—GENERAL WORKS ON PALÆOBOTANY.
In the text frequent reference has been made to special memoirs and reports on the fossil plants of particular regions or formations. There are, however, some general books, useful to students, which may be mentioned here. Perhaps the most important is Schimper’s “Traité de Paléontologie Végétale.” Very useful information is also contained in Renault’s “Cours de Botanique Fossile,” and in Balfour’s “Introduction to Palæontological Botany,” and Nicholson’s “Palæontology.” Unger’s “Genera et Species,” Brongniart’s “Histoire des Végétaux Fossiles,” and Lindley and Button’s “Fossil Flora,” are older though very valuable works. Williamson’s “Memoirs,” in the “Philosophical Transactions,” have greatly advanced our knowledge of the structures of Palæozoic plants. Lastly, the “Palæophytology” of Schenk, now in course of publication in German and French, in connection with Zittel’s “Palæontology,” is an important addition to manuals of the subject.
Acer, [228].
Acrogens, [6].
Agassiz, Prof., [16].
Alaska, Flora of, [245].
Algæ, real and spurious, [26], [230].
Amboy clays, Flora of, [203].
America, Cretaceous of, [190].
Angiosperms, [6].
Annularia, [122].
Anogens, [6].
Antholithes, [132].
Aporoxylon, [25].
Araucarioxylon, [148].
Araucarites, [134].
Archæocalamites, [170].
Archæopteris, [77], [85].
Arctic origin of plants, [221], [238].
Arthrophycus, [30].
Arthrostigma, [67].
Asterophyllites, [78], [122], [170].
Asteropteris, [77], [85].
Astropolithon, [30].
Atané, Plants of, [242], [281].
Atanekerdluk, Plants of, [283].
Australia, Palæozoic flora of, [147].
Tertiary flora of, [217].
Bauhinia, [204].
Bear Island, [241].
Betula, [198].
Bilobites, [28].
Bovey Tracey, Plants of, [226].
Brasenia, [207].
Buckland, Dr., [179].
Buthotrephis, [37].
Calamites, [77], [123], [166].
Calamodendron, [125].
Cambrian flora, [20].
Canada, Erian of, [103].
Carboniferous of, [110].
Laramie of, [209].
Pleistocene of, [227].
Carbon in Laurentian, [9].
Carboniferous flora, [110].
Carboniferous, Climate of, [138].
of Southern Hemisphere, [147].
Cardiocarpum, [82], [153].
Carruthers, Mr., [24], [98], [180].
On modifications of modern plants, [225], [269].
Carya, [196].
Cauda-galli fucoid, [105].
Caulerpites, [29].
Caulopteris, [75], [94].
Clarke, Prof., [51].
Climate, Causes of, [247].
Climate and plants, [216], [220], [232].
of Carboniferous, [138].
of Cretaceous and Eocene, [216].
of Devonian, [47].
of Early Mesozoic, [178].
Climate and plants of Laurentian, [17].
of Pleistocene, [227], [230].
of Pliocene, [223].
Coal, origin of, [117], [139].
Comparison of floras, [272].
Composite, [266].
Cone-in-cone, [36].
Coniferæ, Erian, [78], [96].
Carboniferous, [134], [148].
Mesozoic, etc., [181].
Cope, Mr., [215].
Cordaites, [78], [130], [151].
Corylus, [213].
Crepin, M., [99].
Cretaceous, Flora of, [190].
Climate of, [216].
Croll on climate, [252].
Cromer, Plants of, [224].
Cycads, Mesozoic, [178].
Cyclostigma, [157].
Dadoxylon, [96], [134], [148].
Dawson, Dr. G. M., [52], [210].
Delgado, Prof., [26].
Dendrophycus, [33].
Derby, Orville, [53].
Devonian flora, [45].
Devonian or Erian, [107], [279].
Climate of, [47].
Dicotyledons, Cretaceous, [192].
Table of, [192].
Dictyolites, [33].
Dictyospongia, [39].
Disco, Exotic plants at, [256].
Flora of, [245], [282].
Drepanophycus, [39].
Drosera, [228].
Dunvegan beds, [244].
Eocene, Flora of, [208], [214].
Climate of, [216].
Eophyton, [31].
Eopteris, [72].
Eozoon of Laurentian, [9].
Equisetum, [176], [230].
Erian flora, [45], [279].
Climate of, [47].
Erian or Devonian, [107].
Ettingshausen, Dr., [187], [215].
Exogens, Cretaceous, [192].
Tertiary, [213], [224].
Fagus, [196], [197].
Ferns, Erian, [72].
Carboniferous, [126], [171].
Fructification of, [128].
Stems of, [90], [129].
Tertiary, [212].
Filices, [72], [126], [171].
Flora of Cambrian, [26].
of Carboniferous, [110], [274].
of Cretaceous, [190].
of Early Mesozoic, [175].
of Erian, [45], [279].
of Jurassic, [177], [186].
of Laramie, [209].
of Laurentian, [8].
of Miocene, [220], [223].
of Modern, [219].
of Permian, [274].
of Pleistocene, [223], [227].
of Tertiary, [191], [208], [214], [219].
Fontaine, Prof., [130], [176].
Fontinalis, [230].
Fort Union beds, [210].
Fucoids, [27].
Gardner, Mr. Starkie, [212].
Geinitz, Dr., [174].
Geological formations, Table of, [4].
Glossopteris, [147].
Glyptodendron, [25].
Glyptostrobus, [194].
Goeppert, Dr., [99].
Grant, Col., [36].
Graphite from plants, [8].
Gray, Dr., Origin of floras, [223], [237].
Greenland, Climate of, [216].
Fossil flora of, [247].
Gulielmites, [35].
Gymnosperms, [6].
Haliserites, [39].
Hartt, Prof., [53].
Heer, Dr., [108], [181].
Helderberg period, Sea of, [250].
Heterangium, [77].
Hicks, Dr., [21].
Hunt, Dr. Sterry, [13], [143].
Huxley, Prof., [53].
Hymenæa, [204].
Insects, Erian, [83].
Juglans, [196].
Jurassic flora, [177].
Kainozoic flora, [191], [208], [214], [219].
Kidston, Mr. R., [128], [273].
King, Mr. Clarence, [211].
Komé, Plants of, [242], [281].
Laramie flora, [209], [215].
Laurentian plants, [8].
Laurentian, Climate of, [17].
Laurophyllum, [193].
Laws of introduction of plants, [237], [266].
Leda clay, Flora of, [232].
Lepidodendron, [120], [156], [162].
Lepidophloios, [121], [157], [165].
Leptophleum, [157].
Lesquereux, Mr. L., [169], [214].
Licrophycus, [30].
Lignitic series of America, [208].
Liquidambar, [197].
Liriodendron, [199].
Lower Carboniferous flora, [277].
Logan, Sir W., [48].
Lyell on climate, [249].
Magnolia, [200].
McConnell, Mr., [209].
McNab, Prof., [169].
Megalopteris, [76].
Megaphyton, [129].
Mesozoic flora, [175].
Climate of, [178].
Migrations of plants, [240], [245].
Miller, Hugh, [98].
Miocene flora, [220].
Miocene, Supposed, [242].
Modern flora, [219].
Modern plants, how modified, [269].
Modifications of plants, [266].
Nathorst, Dr., [26], [196].
Nematodendreæ, [25].
Nematophycus, [23].
Nematophyton, [21], [22], [42].
Newberry, Dr., [200], [203], [214].
Newfoundland, Fossil plants of, [242].
Newton, Mr., [52].
Nicholson, Dr. A., [20].
Niobrara series, [243], [246].
Noeggerathia, [130].
Northern origin of plants, [238].
Origin of plants, [237].
Orton, Prof., [51].
Pachytheca, [21].
Palæanthus, [205].
Palæochorda, [30].
Palæophycus, [30], [38].
Palæozoic floras compared, [273].
Palms, [188], [194].
Pandanus, [188].
Patoot beds, [282].
Peach, Mr., [98].
Petroleum, Origin of, [56].
Phymatoderma, [29].
Plants, Classification of, [6].
Platanus, [198].
Platyphyllum, [74].
Pleistocene climate, [227], [230].
Pleistocene flora, [223], [227].
Pliocene climate, [223].
Podozamites, [178].
Poles, Supposed change of, [248].
Populus, [191], [228].
Potamogeton, [229].
Potentilla, [228].
Protannularia, [21].
Protichnites, [27].
Protophyllum, [199].
Protosalvinia, [52].
Protostigma, [20].
Prototaxites, [21].
Psaronius, [93].
Psilophyton, [64].
Ptilophyton, [62], [86].
Quercus, [197].
Rhizocarps, [48].
Rill-marks, [33].
Rusichnites, [28].
Saccamina, [57].
Salisburia, [180].
Salter, Mr., [98].
Salvinia, [54].
Saporta, Count de, [26], [193].
Saportea, [57].
Sassafras, [199].
Scalariform tissue, [70].
Schimper, Dr., [116], [169], [208].
Scolithus, [30].
Scottish Devonian, [98].
Sequoia, [181].
Shrinkage cracks, [33].
Sigillaria, [71], [112], [154].
Southern Hemisphere, [217], [273].
Carboniferous in, [147].
Tertiary in, [217].
Sphenophyllum, [61], [122], [171].
Spirophyton, [38].
Spitzbergen, [241].
Sterculites, [193].
Sternbergia, [137], [152].
Stigmaria, [115].
Stur, Dr., on Sigillaria, [116].
Symphorocarpus, [214].
Syringodendron, [156].
Syringoxylon, [82].
Table of formations, [4].
Tasmania, Fossil plants of, [217], [246].
Tasmanite, [57].
Tertiary period, Flora of, [191], [208], [214], [219].
Tertiary of Australia, [217].
Thallogens, [6].
Thomas, Mr., [51].
Thuja, [213], [229].
Time, Geological, [5].
Trapa, [196].
Tree-ferns, [90], [129].
Triassic flora, [176].
Trigonocarpum, [136], [153].
Tyndall, Prof., [138].
Ulrich, Prof., [57].
Unartok beds, [281].
Ursa stage of Heer, [108], [241].
Walchia, [134], [138].
Ward, Mr. L. T., [192], [212], [215].
Wethered, Mr. E., [52].
White, Dr., [215].
Williams, Prof., [51].
Williamson, Dr., [26], [31], [71], [167].
Williamsonia, [188].
THE END.