P R E F A C E . THE object of tlie following Chapters is to yreseilt n sketch in outline of the TYorlds Life-Syste u-tracii g from the earliest organisms in tlie stratified crust to the forms that no va clorn and people its surface. Tlie niin has been to link the renlote to the recent-the living to the extinct-that tlie general reader may be enablecl to form some intelligible coilception of the whole as a great and continuously-evolvingr scheme of vegetable and animal existences. Tlierc is no attempt whatever to teach anatonlical details or point out specific distinctions-the volume being intended not as a Handbook of Pal eontology, but siniply as a readable sketch for the ii forlnation of those have neither the time nor the preliminary training to avail theinselves of vorks of higher scientific preteasions. And yet the reader will find in these pages a reliable rhumb of the science, as founded on the most recent discoveries, ancl a treatment of its bearings from a higher stand-point than call be converiielltly taken by the mere text-books and manuals of Geology. At a time when the question of Life is receiving a wider audience, such a reszl nt may also be of utility in inclicating the line that separates the assumed and hypothetical from the known and ascertainable and so prevent the unprofessional inquirer from ascribing to Geology what it does not affirm, or from expecting from its teachings what they caiiilot reveal. Designed for the general reader, and delivered in part to popular audiences, the style is, perhaps, somewhat more rhetorical than befits the exactitudes of science but even on this point the Author could not well have done otherwise. His object was to excite rather than satisfy the curiosity of his hearers-to impress them with the universality and uniformity of natural law-believing there can be no true notion of Nature or of Natures requirements while her facts are viewed through the medium of the miraculons. Nor let it be thought that, by recognising in every iristance the fixity and unerring operation of Law, we place a wider distance between the Creator and his works, or that any knowlectge of this kind has a tendency to self-sufficiency or irreverence. On the contrary, he who knows most of creational law, and that the most intimately, stands generally the least in need of the injunction- Put off thy shoes from off tlly feet, for the place vl ereothno u treadest is holy. In treating such a theme as Life-its apparent origin and progress-the writer has necessarily had occasion to allude to subjects on which there is rnuch diversity of opinion to some that are usually approached with uneasy tenderness, as coming in conflict with prevalent beliefs and to others on which the uilited labours of Geologists, during the last fifty years, have thrown but little reliable light or information either case he has expressed his opinions freely, but without dogmatism firmly, but solely under the varranto f Geology and always with a frank admission of the many deficiencies and imperfectioils of that science. d s there is nothing to Be gained bp offending a prejudice where we cannot establish a conviction, he has contented himself by stating vllatG eology affirms, without alluding to what it appears to contradict and as the establishment of truth does not always follow the overturning of error, the espoullder of science may surely be permitted to attempt the one without hazarding an endeavour to accornl lislt h e other. In approaching our subject, therefore,-a subject too often treated as if it lay beyond the pale of natural law,-let it be clearly understood that we are dealing with Life solely in its geological aspects... --This text refers to the Paperback edition.