Reviews — Baron von Toll — The Siberian Cambrian. 133 



The Silurian rocks of Podolia consist chiefly of limestone, and 

 may be divided into three series (Horizonte), each characterized by 

 a more or less independent fauna, which developed and altered 

 (luring the deposition of the series. The lowest series, which occurs 

 in the south-east of the Silurian area, near Studenitza, is very 

 poor in corals and gasteropods, but rich in brachiopods, especially 

 Atrypidfe and Lepttenidae. Among the characteristic species are 

 Strophomena antiquata, Atrypa cordata, A. imbricata, A. Barrandei, 

 A. Thisbe, Pentamerus linguifer, and Glassia compressa. This is 

 con-elated with the Wenlook Shale, and with bed c of Lindstrom's 

 Gotland scale. The middle series has a wider extent, and is exposed 

 along the north bank of the Dniester. It is very rich in corals, 

 such as CynthophjUam articidatum, PtychophyUum truncnhim, Rhizo- 

 j^hylhim gotlandicnm, while gasteropods of the genera Oriostoma 

 (esp. 0. discors, O. globosiim), Jlnrckisonia, and Pleiirotomaria are 

 characteristic and abundant. The brachiopods are represented 

 chiefly by Ehynchonellida3 and Pentamerida^. The series is clearly 

 capable of further subdivision, but in the main is correlated with the 

 English beds from Wenlock Limestone to Aymestry, and with d, e, f 

 of Gotland. The uppermost series occurs towards the north of 

 the area, near Dumanov and Kamenez-Podolsk. Brachiopods pre- 

 ponderate, and among the species may be noticed Spirifer Thetidis, 

 S. robustns, Rhynchonella nymplm, B. Hebe, and Atrypa siiblepida. 

 There are scarcely any moUusca and few trilobites ; but there are 

 some ostracods and the characteristic SJurypteriis Fischeri and 

 Scaphaspis obovatus (?). As local developments are beds of crinoiJ- 

 limestone, in which Crotalocrimis rugosus is the only recognized 

 species. A similar occurrence is characteristic of the Gotland 

 horizons g and h, with which this is correlated. Its English 

 representatives are the Upper Ludlow and Passage Beds. 



It is clear that for the greater part of Silurian time the Podoliaa 

 urea formed a part of the great northern basin in which the rocks of 

 England, Gotland, and North-West Eussia were deposited. It was, 

 however, connected with the Bohemian basin, and this connection 

 increased until in Lower Devonian time the Podolian sea formed 

 a link between Bohemia and the Ural basin. F. A. B. 



HI. — BkitrXge zur Kenntniss des Sibirischen Cambrium, Von 

 Eduard von Toll. Memoires de I'Academie Imperiale des 

 Sciences de St. Petersbourg. Serie viii, vol. viii, No. 10, 1899. 



Contributions to a Knowledge of the Siberian Cambrian. 

 By E. von Toll. 4to ; pp. iv + 57, with 9 woodcuts and 

 8 plates. 



N this memoir Baron von Toll records the discovery of beds of 

 sandstone, shale, and limestone, with Cambrian fossils, in several 

 localities in Eastern Siberia widely separated from each other, which 

 seem to indicate the existence in this region of an extensive basin of 

 Cambrian deposits. The rocks have previously been regarded, 

 owing to an erroneous determination of some imperfect fossils, 



