be rendered intelligible in a general way by the study of the annexed tabulations: The Vegetable Kingdom may be arranged into two grand divisions— the CELLULAR and VASCULAR; and these again, according to their modes of growth and reproduction, into the following groups and classes :I. CELLULAR-Without regular vessels, but composed of fibres which sometimes cross and interlace each other. The Conferva (green scumlike aquatic growths), the Lichens (which incrust stones and decaying trees), the Fungi (or mushroom tribe), and the Alga (or sea-weeds), belong to this division. In some of these families there are no apparent seed-organs. From their mode of growth-viz., sprout-like increase of the same organ-they are known as THALLOGENS or AMPHIGENS, and constitute the lowest orders of vegetation. II. VASCULAR--With vessels which form organs of nutrition and reproduction. According to the arrangement of these organs, vascular plants have been grouped into two great divisions-CRYPTOGAMIC (no visible seed-organs), and PHANEROGAMIC (apparent flowers or seed-organs). These have been further subdivided into the followin classes ascending from the lower to the higher forms:1. CRYPTOGAMS-Without flowers, and with no visible seed-organs. To this class belong the mosses, equisetums, ferns, and lycopodiums. It embraces many fossil forms allied to these families. From their mode of growth-viz., increase at the top or growing point-they are known as ACROGENS. 2. PHANEROGAMIC MONOCOTYLEDONS-Flowering plants with one cotyledon or seed-lobe. This class comprises the water-lilies, lilies, aloes, rushes, grasses, canes, and palms. In allusion to their growth by increase within, they are termed ENDOGENS. 3. PHANEROGAMIC GYMNOSPERMS-This class, as the name indicates, is furnished with flowers, but has naked seeds. It embraces the cycadea or cycas and zamia tribe, and the conifera or firs and pines. In allusion to their naked seeds, these plants are also known as GYMNOGENS. 4. PHANEROGAMIC DICOTYLEDONS-Flowering plants with two cotyledons or seed-lobes. This class embraces all forest-trees and shrubs-the composita, leguminosæ, umbelliferæ, cruciferæ, and other similar orders. None of the other families of plants have the true woody structure, except the coniferæ or firs, which seem to hold an intermediate place between monocotyledons and dicotyledons; but the wood of these is readily distinguished from true dicotyledonous wood. From their mode of growth-increase by external rings or layers-they are termed EXOGENS. SPERMOCARPS (Seed-Fruits.) SCHEME OF VEGETABLE CLASSIFICATION. ANGIOSPERMS (Enclosed Seeds.) Trees, Shrubs, Herbs. EXOGENS....... DICOTYLEDONS. (Increase from without.) (Two Seed-Lobes.) ENDOGENS......MONOCOTYLEDONS......Grasses, Sedges, Palms. (from within.) (One Seed-Lobe.) GYMNOSPERMS... GYMNOGENS ..... POLYCOTYLEDONS (Naked Seeds.) from without.) (Many Seed-Lobes.) ...Cycads and Conifers. ANGIOSPORES... ACROGENS... (Enclosed Spores.) (from the point.) (Leaf-Growths.) AXOGAMS. ..Mosses and Liverworts. HYSTEROPHYTES ..Fungi or Mushrooms. (Ultimate or Lowest Growths.) Subdividing still further, according to their most marked characteristics, whether external or internal, the botanist arranges all the known forms of Vegetable Life into some 300 orders, upwards of 9000 genera, and about 120,000 species. As the most of these distinctions, however, are founded on the form and connection of the flower, fruit, and leaf-organs which rarely or never occur in connection in a fossil state-the palæontologist is guided in the main by the great structural distinctions above adverted to, and not unfrequently by the simple but unsatisfactory test of "general resemblance." The flower and the organ of fructification may have perished, but still the form and venation of the leaf, the external sculpturing of the bark, the disposition of the leaves and branches, and the general mode of growth, may be preserved; and from these, as well as from the microscopic examination of the lapidified tissues, the palæophytologist can for the most part determine, or at all events approximate to the determination of, his fossil twigs and fragments. So certain, indeed, are the determinations of the microscope, that where good sections can be procured, the competent observer rarely or never fails to establish the great order to which the organism belongs; and this, considering the difficulties surrounding palæophytology, is a triumph of no mean description. As the palæophytologist, in arranging his fossil organisms, is guided by the classification of the botanist, so the palæozoologist follows, as closely as the nature of his objects will permit, the systematic schemes of the zoologist. And in this he has altogether an easier task, inasmuch as animal organisms, from their less destructible nature, are in general more perfectly and legibly preserved. The horny and calcareous structures of zoophytes, corals, shells, crusts of crustacea, calcareous tubes of annelids, chitonous wing-sheaths of insects, and the like, are well-known instances of this comparative indestructibility among the invertebrata; while bony scales and scutes, horns, bones, and teeth, are still more familiar examples, perhaps, among the vertebrata. In this way, partly by external form, partly by internal structure, and partly by the great anatomical law of the co-relation of parts, the palæozoologist is enabled to arrive at determinations more satisfactory, on the whole, than those of the palæophytologist. Species, genera, families, and even whole orders, may be extinct; but, comparing his organisms with the existing, he finds their nearest affinities, and assigns them their place in the systematic arrangements of the zoologist. For this purpose the subjoined scheme is in general sufficient, and its study in this place will greatly facilitate the reader's comprehension of what may be subsequently stated respecting the fossils of the different formations : SCHEME OF ANIMAL CLASSIFICATION. VERTEBRATA, Or animals with backbone and bony skeleton, and comprehending MAMMALIA, AVES, REPTILIA, and PISCES. I. MAMMALIA, or Sucklers; subdivided into Placental and Aplacental. 1. PLACENTAL, bringing forth mature young. BIMANA (Two-handed)-Man. QUADRUMANA (Four-handed)-Monkeys, Apes, Lemurs. RODENTIA (Gnawers)-Hare, Beaver, Rat, Squirrel, Porcupine. PACHYDERMATA (Thick-skins)—Elephant, Hippopotamus, Rhinoceros. 2. APLACENTAL, bringing forth immature young. MARSUPIALIA (Pouched)--Kangaroo, Opossum, Pouched Wolf. MONOTREMATA (One-vented)—Ornithorhynchus, Porcupine-ant-eaters. II. AVES, or BIRDS. RAPTORES (Seizers)-Eagles, Falcons, Hawks, Owls, Vultures. INSESSORES (Perchers)-Jays, Crows, Finches, Sparrows, Thrushes. SCANSORES (Climbers)-Woodpeckers, Parrots, Paroquets, Cockatoos. COLUMBE (Pigeons)-Common Dove, Turtle Dove, Ground Dove. RASORES (Scrapers)—Barnfowl, Partridge, Grouse, Pheasant. CURSORES (Runners)-Ostrich, Emu, Apteryx. GRALLATORES (Waders)-Rails, Storks, Cranes, Herons. NATATORES (Swimmers)--Divers, Gulls, Ducks, Pelicans. III. REPTILIA, subdivided into Reptiles Proper and Batrachians. 1. REPTILES PROPER. CHELONIA (Tortoises)-Turtles, Tortoises. LORICATA (Covered with Scutes)-Crocodile, Gavial, Alligator. 2. BATRACHIANS, or FROGS. ANOURA (Tail-less)-Toad, Frog, Tree-Frog. IV. PISCES, or FISHES. SELACHIA (Cartilaginous)-Chimæra, Sharks, Sawfish, Rays. INVERTEBRATA, Or animals void of backbone and bony skeleton, and comprehending ARTICULATA, MOLLUSCA, RADIATA, and PROTOZOA. I. ARTICULATA, subdivided into Articulates and Vermes. 1. ARTICULATA, or Jointed Animals Proper. INSECTA (Insects)-Beetles, Butterflies, Flies, Bees. |