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allied ambulacral animals aperture appear arms arranged attached basals base become belonging body branches calcareous calyx canals Carboniferous carry central chamber characteristic characters closely colony commonly comparatively completely composed comprises condition connected consists corallites corallum corals Cretaceous Crinoids deposits developed Devonian disc distinct divided division dorsal ends enlarged entire existing fact five formation forms fossil four genera genus give grooves hand included Jurassic known lateral layer less limestones living lower margin minute mouth natural occur Ordovician organisms Original pairs perforated period placed plates pores portion position possess present principal produced radial range recent referred regarded remains represented rocks rows separated septa shell showing side Silurian similar simple single skeleton sometimes species spicules Sponges structure surface tabulae Tertiary tubes types upper usually valve vertical wall
עמוד iii - NICHOLSON. A Manual of Zoology, for the use of Students. With a General Introduction on the Principles of Zoology. By HENRY ALLEYNE NICHOLSON, MD, D.Sc., FLS, FGS, Regius Professor of Natural History in the University of Aberdeen.
עמוד 136 - 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...
עמוד 136 - Egypt, where it was largely quarried of old for the building of the Pyramids, into Asia Minor, and across Persia, by Bagdad, to the mouths of the Indus. It...
עמוד 136 - According to Sir Charles Lyell, " the Nummulitic Limestone, 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 in Algeria or Morocco.
עמוד 13 - formation," which I have used in the above explanation, expresses in geology any assemblage of rocks which have some character in common, whether of origin, age, or composition.
עמוד 98 - Every species has come into existence coincident both in space and time with a pre-existing closely allied species.
עמוד 674 - Dorsal valve with a loop consisting of two delicate riband-like lamellae, which extend about one-half the length. These lamellae at first curve gently outwards, and then approach each other gradually, until at their lower extremities they meet at an acute angle ; then becoming united, they are reflected backwards towards the beak in what appears to be a thin flat vertical plate. Near their origin, each bears upon the ventral side a single triangular crural process.
עמוד 104 - It cannot be doubted, therefore, that palaeontology has, so far, to a large extent, failed to bring forward the numerous and closely graduated series of intermediate forms which must at one time have existed, supposing ' natural selection ' to be the sole agent in the origination of new species. The absence of a sufficient number of such transitional forms, and the insufficient connection between such as are known to exist, may doubtless be in part explained by the known ' imperfection of the geological...
עמוד 487 - As might be expected, the markings above referred to, when in relief, occur on the under sides of the beds. A few instances may, however, be found where they exist on the upper surfaces. On careful consideration of these raised impressions, I have arrived at the conclusion that they have been left by denudation of the surrounding material, just as footprints on dry snow sometimes remain in relief after the surrounding loose snow has been drifted away by the wind ; the portion consolidated by pressure...
עמוד 363 - SeaUrchins, the Star-Fishes, the Brittle-Stars, the Sea-Cucumbers, &c. They are furnished with an exoskeleton of carbonate of lime, and are well preserved in a fossil state. " Each plate, spine, and joint are mineralogically and optically, as it were, made out of a single crystal of calcite, having its principal axis perpendicular to the plane of the plate, or parallel to the axis of a spine or joint, the growth being from first to last in perfect crystalline continuity.