The fauna has already been noticed. It consists of brachiopods, some of which are of peculiar genera. The general similarity of the faunas in regions so remote as Spitsbergen, the Ural Mountains, India, and New South Wales, indicates an extensive sea during the period. It can hardly be supposed that the fauna of Permo-Carboniferous times has been completely described, for the fossils of one or two areas only have been made known to us with any degree of fulness, and when the Permo-Carboniferous and marine Permian faunas are as well known as those of Triassic times (and the latter have only been fully described very recently) there is no doubt that the important break which was at one time supposed to exist between Palæozoic and Mesozoic faunas will be filled in satisfactorily[95]. [Footnote 95: The Permo-Carboniferous beds are described in Messrs Medlicott and Blanford's _Geology of India_, second edition (edited by Mr R. D. Oldham), and figures of some of the important fossils given therein. For fuller information the reader should refer to Waagen's account of the Salt Range Fossils and Feistmantel's description of the plants in the _Memoirs of the Geological Survey of India_.] CHAPTER XX. THE PERMIAN SYSTEM. _Classification._ It has already been observed that as the result of the Pennine and Mendip systems of earth-movement, the Carboniferous rocks of Britain are succeeded by a marked unconformity, and that the rocks of the succeeding Permian and Triassic systems of Britain shew an abnormal development. The principal areas where Permian rocks are found are on either side of the Pennine Chain in the North of England, but sporadic exposures of rocks of this age are found in some of the Midland and Southern counties. The Permian rocks have been well studied in Germany, and the German names are sometimes adopted in Britain, and the following comparison will prove useful:-- Britain. Germany. Magnesian Limestone Magnesian Limestone } Zechstein. Marl Slate Kupferschiefer } Lower Permian Sandstones Rothliegende. The term Zechstein has been applied in a somewhat different sense by different writers, but the one given in the table appears to find most favour. In a region which was essentially continental, considerable variations in the lithological characters of the rocks may be expected, when the strata are traced laterally, but we nevertheless find that the differences are not so great as was formerly supposed to be the case when certain red sandstones lying above recognised Permian strata in the district on the west side of the Pennine Chain towards its northern extremity were also referred to the Permian; these sandstones (the St Bees Sandstones) are now generally admitted to be of Triassic age, and comparison between the rocks on opposite sides of the Pennine Chain is much simplified, as seen below.