196 HISTORICAL PALEONTOLOGY. 



deposits of this age with which we are as yet acquainted. Red 

 rocks are, as a general rule, more or less completely unfossil- 

 iferous, and sediments of this nature are highly characteristic of 

 the Permian. Similarly, magnesian limestones are rarely as 

 highly charged with organic remains as is the case with normal 

 calcareous deposits, especially when they have been subjected 

 to concretionary action, as is observable to such a marked ex- 

 tent in the Permian limestones. Nevertheless, much interest 

 is attached to the organic remains, as marking a kind of transi- 

 tion-period between the Palaeozoic and Mesozoic epochs. 



The plants of the Permian period, as a whole, have a dis- 

 tinctly Palaeozoic aspect, and are far more nearly allied to those 

 of the Coal-m?asures than they are to those of the earlier 

 Secondary rocks ; though the Permian species are mostly dis- 

 tinct 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 Sigillarioids 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 Carbon- 

 iferous genera Alethopteris, Ncuropieris, Sphenopteris, and Pecop- 

 teris. There are also Tree-ferns referable to the ancient genus 

 Psaronius. The Confers 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 



Fig. 134. Walchia piniforjttis, from the Permian of Saxony. 

 a, Branch ; b, Twig. (After Gutbier.) 



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 



