As preliminary to the subject here to be presented, we must bear in mind that the present arrangement of the fossils in alleged chronological order, as well as the naming of thousands of typical specimens, was all well advanced while as yet little or nothing was known of the contents of the depths of the ocean, or even of the land forms of Africa, Australia, and other foreign countries. In most of the important groups of both plants and animals, the detailed knowledge of the fossil forms preceded the knowledge of the corresponding living forms, just as Zittel says that the theories of the igneous origin of the crystalline rocks "had been laid without the assistance of chemistry" and the knowledge of the microscopic structure of these rocks.[40] On pp. 128-137 of his "History," this author shows how, up to 1820, little or nothing of a scientific character was known of any of the classes of living animals save mammals. During the last half century, however, the progress of science has been steadily showing case after case where families and genera, long boldly said to have been "extinct" since "Palaeozoic time," are found in thriving abundance and in little altered condition in unsuspected places all over the world. And the point for consideration here is the manifest absurdity of these inhabitants of the modern seas and the modern land =skipping= all the uncounted millions of years from "Palaeozoic times" down to the "recent," for, though found in profuse abundance in these "Older" rocks, not a trace of many of them is to be found in all the "subsequent" deposits. The proposition here to be considered and proved I shall venture to formulate as follows: =There is a fossil world, and there is a modern living world; the two resembling one another in various details as well as in a general way; but to get the ancestral representatives of many modern types, e.g., countless invertebrates, with other lower forms of animals and plants, we must go clear back to the Mesozoic or the Palaeozoic rocks, for they are not found in any of the "more recent" deposits.= I have already remarked that the blending of the doctrine of life succession with that of uniformity, must inevitably have given birth to the evolution theory, for it is evident that the succession from the low to the high could only have taken place by each type blending with those before and those after it in the alleged order of time. That such is not the testimony of the rocks, even when arranged with this idea in view, is too notorious to need any words of mine, for it has been considered by many[41] the "greatest of all objections" to the theory of evolution. This abruptness in the disappearance of "old" and the first appearance of "new" forms, has brought into being that "geological scape-goat," as James Geikie has called the doctrine of the =imperfection of the record=. But Dawson has well disposed of this argument in the following words: