264: A. E. Ortmann — Climatic zones in Jurassic times. 



directly (1871, p. 521), that there are present palaeontological 

 differences between deposits of both " with the development 

 of facies and conditions of formation apparently in complete 

 agreement" (" bei offenbar ganz iibereinstimmender Facies- 

 entwieklung und Bildungsverhaltnissen "). The facies of these 

 two provinces are, according to him, " apparently " the same, 

 but he does not give any proof for it. It is true, limestone- 

 facies prevail in both, and it may be that Neumayr thought of 

 this fact. There is, however, no doubt that all. the known 

 limestone-deposits were not formed under the same condi- 

 tions ; the Coral-limestones and the Cephalopod-limestones of 

 the Middle-European province are certainly different facies ; 

 the Aptychus-limestone of the Mediterranean province is 

 characterized by its petrographic nature (Horn stone lime- 

 stone) due to the presence of silicious matter, and the Ceph- 

 alopod-limestones of the latter province are also probably 

 different. It is well known that all these deposits are differ- 

 ent petrographically, and after a more close, especially micro- 

 scopical examination, we will be, perhaps, enabled to find out 

 the causes of their differences. 



Yet we do not need much to urge these differences in these 

 two provinces, as we saw above that the main differences are 

 given by the different depths of the respective seas. To 

 distinguish the Middle-European and Russian provinces, 

 however, we have to direct more attention to the facies. The 

 differences of the facies in the two latter provinces are wholly 

 neglected by Neumayr, although they were pointed out most 

 vigorously by Lahusen * and Kikitin. 



It was a well known fact, even to Neumayr, that in the 

 Middle-European province limestones prevail, especially if we 

 consider the upper strata (1890, p. 316), while in the Russian 

 Jura " more soft clays and sands " (p. 326), and only " in an 

 inferior degree limestones" (p. 327) are found. This preva- 

 lence of sandstones, especially in the Aucella beds, is stated by 

 Lahusen several times (1. c. p. 486, p. 491, p. 492), and Kiki- 

 tin (1. c. 1886, p. 211, p. 237) eveu holds this peculiarity of 

 the facies responsible for the faunistic differences. It is 

 further a very' interesting fact given by Nikitin (p. 217, p. 234, 

 p. 236), that corals are found in some places of the Russian 

 Jura, and these are true Reef-corals belonging to the Tham- 

 na8trceido3. Neumayr refers (1887, p. 72) to this statement 

 only by saying, that the occurrence of corals in Russia is " very 

 rare," and that (p. 73) against the view that conditions of the 

 facies play part here " grave doubts exist " (" schwere Beden- 



* Uber die jurassichen Bildungen im sudwestlichen Teile des Gouvernements 

 Rjasan.— Neues Jahrb. Min. Geol. Pal. 1877. 



