ABSTRACT
Fossils are exclusively found in the so-called sedimentary deposits which form the upper part of the earth’s crust. According to W. Gothan the graphite masses which are found even in the Primary rocks point with certainty to the existence of organic growths. With the numerical increase of the individuals both animals and plants naturally incur the necessity of dividing their resorts or habitats, they occupy different elevations in valleys or on the mountains, deeper or shallower water, and more humid or drier climates. The ‘evolutionary series’ of some organisms, the course of which may be followed more or less without hiatus, never present such considerable deviations from each other that the new forms must be arranged ‘in separate natural families.’
