We know only two living species of _Sequoia_, both of which are confined to California. The one (_S. sempervirens_) is clothed with erect leaves, arranged in two rows, very much like our yew-tree, and bears small, round cones; the other (_S. gigantea_) has smaller leaves, set closely against the branches, giving the tree more the appearance of the cypress. The cones are egg-shaped, and much larger. These two types are, therefore, sharply defined. Both of these trees have an interesting history. If we go back into the Tertiary, this same genus meets us with a long array of species. Two of these species correspond to those living at present: the _S. Langsdorfii_ to the _S. sempervirens_, and the _S. Couttsiæ_ to the _S. gigantea_. But, while the living species are confined to California, in the Tertiary they are spread over several quarters of the globe. Let us first consider the _Sequoia Langsdorfii_. This was first discovered in the lignite of Wetterau, and was described as _Taxites Langsdorfii_. Heer found it in the upper Rhone district, and there lay beside the twigs the remains of a cone, which showed that the _Taxites Langsdorfii_ of Brongniart belonged to the Californian genus _Sequoia_ established by Endlicher. He afterward found much better preserved cones, together with seeds, along with the plants of east Greenland, which fully confirmed the determination. At Atanekerdluk in Greenland (about 70° north latitude) this tree is very common. The leaves, and also the flowers and numerous cones, leave no doubt that it stands very near to the modern redwood. It differs from it, however, in having a much larger number of scales in the cone. The tree is also found in Spitzbergen at nearly 78° north latitude, where Nordenskiöld has collected, at Cape Lyell, wonderfully preserved branches. From this high latitude the species can be followed down through the whole of Europe as far as the middle of Italy (at Senegaglia, Gulf of Spezia). In Asia, also, we can follow it to the steppes of Kirghisen, to Possiet, and to the coast of the sea of Japan, and across to Alaska and Sitka. It is recognized by Mr. Starkie Gardner as one of the species found in the Eocene of Mull in the Hebrides. It is thus known in Europe, Asia, and America from 43° to 78° north latitude, while its most nearly related living species, perhaps even descended from it, is now confined to California. With this _S. Langsdorfii_, three other Tertiary species are nearly related (_S. brevifolia_, Hr., _S. disticha_, Hr., and _S. Nordenskiöldi_, Hr.). These have been met with in Greenland and Spitzbergen and one of them has been found in the United States. Three other species, in addition to these, have been described by Lesquereux, which appear to belong to the group of the _S. Langsdorfii_, viz., _S. longifolia_, Lesq., _S. angustifolia_, and _S. acuminata_, Lesq. Several species also occur in the Cretaceous and Eocene of Canada.