This tree is at once distinguished from the Redwood by its ovate, sharply pointed and stiffer leaves which retain their spiral disposition and closely surround the axis of the twigs like obliquely-set needles. The cones are of the same type as those of _Sequoia sempervirens_, but are broader and may attain a length of 3-1/2 inches (9·5 cm.) (Fig. 14). Reference has already been made to Sequoia as a striking illustration of longevity. It is also selected as an equally impressive example of a type verging on extinction, which played a prominent part in the vegetation of both west and east during the Cretaceous and Tertiary periods. [Illustration: Fig. 14. _Sequoia gigantea_ Torr. (7/8 nat. size.)] Scraps of branches with leaves hardly distinguishable from those of the existing Californian trees are frequently met with in Tertiary and Mesozoic sediments, and with them occasionally occur cones too imperfectly preserved to afford satisfactory evidence of more than superficial agreement with those of the recent species. The task of deciphering the past history of plants, particularly of the Conifers, is accompanied by many difficulties and insidious temptations. It is clear from a critical examination of many of the recorded instances of fossil Sequoias that the generic name has been frequently used by writers without adequate grounds. The fragmentary specimens available to the botanical historian cannot as a rule be subjected to microscopical investigation, and even a partial acquaintance with the similarity of the foliage of different types of living Conifers is sufficient to convince the student of the need of self-control in the identification of the fossils. It is, however, easy to point out obvious pitfalls, though difficult to maintain a judicial attitude in the excitement of endeavouring to interpret documents which are too incomplete to be identified with certainty. If we put on one side all records of supposed fossil Sequoias not based on satisfactory data, there remains a wealth of material testifying to the antiquity of the surviving species.