A Manual of Palaeontology for the Use of Students with a General Introduction on the Principles of PalaeontologyW. Blackwood and sons, 1872 - 601 páginas |
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Términos y frases comunes
abundant allied ambulacral anchylosed animal aperture appear appendages arms articulated attained beak beds belong Birds Bivalves body bones bony Brachiopods calcareous calyx Cambrian Carboniferous Carboniferous Rocks Cephalopods Chalk characterised commence composed comprising consists coral Cretaceous Cretaceous period Crinoids Crustaceans deposits Devonian division dorsal Eocene Eocene Tertiary existing extinct feet fins fishes Foraminifera formation forms fossil Ganoids genera genus gills Graptolites horny Hydrozoa incisors integument Jurassic known Lastly latter less limbs Limestone living lower jaw Lower Silurian Mammals margin Mesozoic Miocene molars Mollusca mouth occur Oolites operculum pair Paleozoic pectoral Permian placed plants plates Pliocene Polyzoa possession Post-Pliocene Post-Tertiary posterior present day regarded remains represented Reptiles ribs Sandstone segments septa shell side Silurian Rocks single siphuncle skeleton sometimes spines strata structure sub-kingdom sub-order surface tail teeth toes Trias Triassic tube Upper Cambrian Upper Silurian usually vertebræ vertebral column whilst whorls Zoantharia
Pasajes populares
Página 372 - Ichthyosaurus to cut through the waves. May it not therefore be concluded (since, in addition to these circumstances, its respiration must have required frequent access of air), that it swam upon or near the surface, arching back its long neck like a swan, and occasionally darting it down at the fish which happened to float within its reach.
Página 66 - The nummulitic formation, with its characteristic fossils, plays a far more conspicuous part than any other tertiary group in the solid framework of the earth's crust, whether in Europe, Asia, or Africa. It often attains a thickness of many thousand feet, and extends from the Alps to the Carpathians, and is in full force in the north of Africa, as, for example, in Algeria and Morocco. It has...
Página 7 - ... by its own action. Upon every coast-line the sea is constantly eating back into the land and reducing its component rocks to form the shingle and sand which we see upon every shore. The materials thus produced are not, however, lost, but are ultimately deposited elsewhere in the form of new stratified accumulations, in which are buried the remains of animals inhabiting the sea at the time. Whenever, then, we find anywhere in the interior of the land any series of beds having these characters...
Página 371 - ... paddles ; that it was marine is almost equally so from the remains with which it is universally associated ; that it may have occasionally visited the shore, the resemblance of its extremities to those of the turtle may lead us to conjecture ; its...
Página 404 - ... as is also that tooth in the lower jaw which, in opposing it, passes in front of its crown when the mouth is closed. The other teeth of the first set are the ' deciduous molars ; ' the teeth which displace and succeed them vertically are the ' premolars ; ' the more posterior teeth, which are not displaced by vertical successors, are the ' molars,
Página 372 - ... darting it down at the fish which happened to float within its reach. It may, perhaps, have lurked in shoal water along the coast, concealed among the seaweed, and raising its nostrils to a level with the surface from a considerable depth, may have found a secure retreat from the assaults of dangerous enemies ; while the length and flexibility of its neck may have compensated for the want of strength in its jaws, and its incapacity for swift motion through the water, by the suddenness and agility...
Página 480 - Stems branching dichotomously, and covered with interrupted ridges. Leaves rudimentary or short, rigid and pointed ; in barren stems, numerous and spirally arranged; in fertile stems and branchlets sparsely scattered or absent; in decorticated specimens represented by minute punctate scars. Young branches circinate ; rhizomata cylindrical, covered with hairs or ramenta, and having circular areoles irregularly disposed, giving origin to slender, cylindrical rootlets. Internal structure, an axis of...