[Sidenote: Fig. 92. _Pinites ovatus_ (_Zamia ovata_ of Lindley and Hutton), an ovate cone with a truncated base and obtuse apex, nearly allied to the stone-pine.]
The Tertiary period is characterised by the abundance of Angiospermous Dicotyledons and of Monocotyledons, more especially of Palms. By this it is distinguished from the more ancient periods. Angiosperms at this period greatly exceed Gymnosperms. Cycadaceæ are very rare, if not completely wanting, in the European Tertiary strata, and the Coniferæ belong to genera of the temperate regions. In the lower Tertiaries Carruthers has found a fossil Osmunda, and the existence of a group of Pines having cones with a very thick apophysis. From their remarkable external aspect, these cones had been considered to be Cycadean, but their internal structure indicates that they are coniferous. Pinites ovatus is one of these cones (Fig. 92). The Cupressineæ are found in the Tertiary beds only. Taxodieæ are represented by Sequoiites (Plate II. Fig. 7) in the Cretaceous and Eocene strata. Peuce australis of Van Diemen's Land and P. Pritchardi of Ireland are Tertiary plants. The Peuce of Eigg (P. Eggensis), according to Geikie, is also Tertiary, and not Oolitic. Isoetes is mentioned by Schimper as a Tertiary genus. Although the vegetation throughout the whole of the Tertiary period presents pretty uniform characters, still there are notable differences in the generic and specific forms, and in the predominance of certain orders at different epochs. Brongniart does not entirely agree with Unger as to these epochs. Many of the formations classified by Unger in the Miocene division he refers with Raulin to the Pliocene. He divides the Tertiary period, as regards plants, into the Eocene, Miocene, and Pliocene epochs, and gives the following comparative results from an examination of their floras:--
+-----------------+---------------+----------------+-----------------+ | Classes and | | | | | Sub-Classes. | Eocene Epoch. | Miocene Epoch. | Pliocene Epoch. | +-----------------+---------------+----------------+-----------------+ | Thallogenæ | 16 | 6 | 6 | | Acrogenæ | 17 | 4 | 7 | | Monocotyledones | 33 | 26 | 4 | | Dicotyledones-- | | | | | Gymnospermæ | 40 | 19 | 31 | | Angiospermæ | 103 | 78 | 164 | +-----------------+---------------+----------------+-----------------+ | | 209 | 133 | 212 | +-----------------+---------------+----------------+-----------------+