344 STKATIGRAPHICAL GEOLOGY 



marls, partly lacustrine and partly marine, the fauna including 

 some survivals from the Carboniferous, such as Productus cora, 

 P. punctatus, and a species of Phillipsia, but associated with a 

 new and peculiar set of Ammonoids, i.e. Medlicottia, Popanoceras, 

 Agathiceras, and Thalassiceras. The plant remains again are chiefly 

 Permian forms, including Catamites gigas and Callipteris conferta, 

 with several species of Walchia and Ullmannia. This set of beds 

 was called the Artinskian stage by Karpinsky in 1874, and it is 

 clearly a marine representative of the western Autunian. 



In the same area, overlying the Artinskian, is Sibertzew's n 

 Kosstroma stage, which is evidently the equivalent of the 

 Saxonian. It presents two facies, the one of marls and sandstones 

 (some grey and some red), containing plant remains with Carbonicola 

 and bones of Palcaoniscus and Archegosaurus ; the other consisting 

 of various kinds of limestone (oolitic, compact, marly, etc.), with 

 a marine fauna, including Productus Cancrini, Athyris Roissyi, 

 Dielasma elongatum, and Bakevellia parva. 



Still higher are limestones with many Zechstein fossils, but it 

 is noteworthy that Productus Cancrini takes the place of P. horridus, 

 and Strophalosia horrescens that of S. Goldfussi. These are overlain 

 by red sandy marls, containing freshwater Unionidee (Naiadites 

 and Palceomutela), which Nikitin proposed to call the " Tartarian 

 stage." If adopted as an equivalent for the whole of the Russian 

 Thuringian the name might be useful. 



In Vologda (Northern Russia), near the sources of the Little 

 Dwina and Suchona, certain marls and sandstones belonging to 

 the upper stage have acquired importance from Amalitsky's 

 discovery in them of the remains of many reptiles Pareiasaurus, 

 Dicynodon, Ehopalodon, Elginia, Gordonia, and others, associated 

 with many Unionidas (Paltxanodon, Palceomutela, Oligodon, Carboni- 

 cola, etc.), and a flora of mixed Asiatic and European types, i.e. 

 species of Glossopteris and Gangamopteris,vfiih.Callipteris, Tceniopteris, 

 Schizoneura, etc. 12 



E. HISTORY OF THE PERIOD 



From the stratigraphical facts, which have been summarised in 

 the preceding pages, we may gather that the Permian period was a 

 natural continuation of the Carboniferous, and that the earliest 

 Permian sediments were accumulated in the same areas and under 

 almost the same physical conditions as those of the preceding 

 Stephanian epoch. 



The western half of the European area was clearly part of a 

 large continent which extended westward far into the Atlantic 



