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Rh an endless variety of species widely different, in form, size and structural complexity. They exist under all the conditions of life, from the dense jungle of the Tropics to the home of eternal snows. In the ordinary walks of life we meet them everywhere, dominating our woodlands, prairies, meadows and ponds. The pedigree of a goodly number, including many dicotyledons (oaks, birches, hollies, etc.), as well as a few monocotyledons (palms, etc.), has been traced as far back as the Upper Cretaceous system. Their rapid evolution in recent geological times was characterized by Darwin as an "abominable mystery." But it is now suggested that their close relationship with insect life is a probable explanation of this mystery. In support of this idea it has been observed that the principal insects concerned in the fertilization of flowers came into being much about the same time, i.e. towards the end of the Cretaceous period. But, however this may be, the world-wide transformation, caused by the sudden rise and rapid evolution of the Flowering Plants, had a corresponding depressive influence on the Gymnosperms, Lycopods, Ferns, and Equisetums, which previously dominated the Plant world. Although many of these Cryptogams have still representatives within British lands, they occupy a subordinate position in comparison with the Angiosperms. Among Gymnosperms, the Coniferæ are the most interesting and conspicuous survivals to our day, still numbering some 300 species. They