Ivi PPvOCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Eut these two formations are also easily distinguished by their 

 rocks ; the schists of </ 2 contain numerous calcareous nodules of a 

 light colour, which are altogether wanting in the bed Ji 1, where the 

 calcareous element only appears at its base in thin bands, and with 

 an entirely different petrographical character from that of the 

 nodules above mentioned. Thus there is sufficient evidence to pre- 

 vent the possibility of mistaking these two beds, g 2 and h 1. 



In the next chapter (3rd) the author describes the stratigraphical 

 relations between the Stages G and H and the other Stages of the Bo- 

 hemian basin. The different sections from various localities are given 

 in great detail, and several faults are described, the explanation of 

 which, Avhen the adjacent beds were unfossiliferous, was a work of 

 much labour and time. I must refer you to the work itself (p. 102) 

 for an account of the fault of Branik and the adjacent colony of 

 Branik, where, in the midst of the Stage D 5, consisting of unfos- 

 siliferous beds of grey schists and quartzites of great thickness, thin 

 fossiliferous bands occur, more or less charged with calcareous 

 matter, containing several species of fossils, which peculiarly charac- 

 terize the lower beds of Stage G ; thus, according to Mr. Barrande's 

 theory, foreshadowing by colonization the future characteristic popu- 

 lation of the overlying beds. Other colonial appearances are de- 

 scribed, as well as a section showing the complete series of the thin 

 bands of Stage G, with the overlying Stage H, in regular conformable 

 stratification. 



In the fourth chapter the author enters into a detailed consider- 

 ation as to how far the Stages G and II are represented in other 

 Silurian basins. The countries thus noticed are England, Eussia, 

 Sweden, Korway, Thuringia, Saxony, Franconia, the Harz, France, 

 Spain, Sardinia, and the United States of America. 



M. Barrande observes that he still adheres to the opinion, pub- 

 lished in his ' Notice preliminaire,' and confirmed twelve years ago 

 in his 'Esquisse Geologique' (Syst. Sil. &c.. Book I.), that, although 

 there was a complete general correspondence between the great 

 Silurian divisions of Bohemia and England, a more detailed compari- 

 son of local forms proves that the different Stages in each countiy 

 did not correspond with each other. Comparing the Upper Silurian 

 formation of England with the faune troisieme of Bohemia, viz. the 

 etages'Ei,'F, G, H, he says that the fossils which characterize the upper 

 division in England and in Bohemia, taken as a whole, constitute, 

 both by their analogies and their identities, whether generic or 

 specific, one simple general fauna, which he calls " faune troisieme." 

 At its commencement in each country this fauna shows a close and 

 intimate resemblance; but, owing to local conditions, or other 

 unknown causes, it has undergone in each country a different 

 development, ^s is shown both by the unequal distribution of each 

 class and by the modifications caused by the extinction and pro- 

 gressive renewal of species. The consequence of this divergence 

 gradually increasing in time has been, that the beds which form the 

 upper portion of the upper division are connected together by a 

 minimum of palseontological relations, so that no individual paral- 



