The _plants_ of the Permian period, as a whole, have a distinctly Palæozoic aspect, and are far more nearly allied to those of the Coal-measures than they are to those of the earlier Secondary rocks; though the Permian _species_ are mostly distinct from the Carboniferous, and there are some new genera. Thus, we find species of _Lepidodendron, Calamites, Equisetites, Asterophyllites, Annularia_, and other highly characteristic Carboniferous genera. On the other hand, the _Sigillariods_ of the Coal seem to have finally disappeared at the close of the Carboniferous period. Ferns are abundant in the Permian rocks, and belong for the most part to the well-known Carboniferous genera _Alethopteris, Neuropteris, Sphenopteris_, and _Pecopteris_. There are also Tree-ferns referable to the ancient genus _Psaronius_. The _Conifers_ of the Permian period are numerous, and belong in part to Carboniferous genera. A characteristic genus, however, is _Walchia_ (fig. 134), distinguished by its lax short leaves. This genus, though not exclusively Permian, is mainly so, the best-known species being the _W. Piniformis_. Here, also, we meet with Conifers which produce true cones, and which differ, therefore, in an important degree from the Taxoid Conifers of the Coal-measures. Besides _Walchia_, a characteristic form of these is the _Ullmania selaginoides_, which occurs in the Magnesian Limestone of Durham, the Middle Permian of Westmorland, and the "Kupfer-schiefer" of Germany. The group of the _Cycads_, which we shall subsequently find to be so characteristic of the vegetation of the Secondary period, is, on the other hand, only doubtfully represented in the Permian deposits by the singular genus _Noeggerathia_. The _Protozoans_ of the Permian rocks are few in number, and for the most part imperfectly known. A few _Foraminifera_ have been obtained from the Magnesian Limestone of England, and the same formation has yielded some ill-understood Sponges. It does not seem, however, altogether impossible that some of the singular "concretions" of this formation may ultimately prove to have an organic structure, though others would appear to be clearly of purely inorganic origin. From the Permian of Saxony, Professor Geinitz has described two species of _Spongillopsis_, which he believes to be most nearly allied to the existing fresh-water Sponges (_Spongilla_). This observation has an interest as bearing upon the mode of deposition and origin of the Permian sediments.