the Devonian Bocks of Moravia. 75 



I emphatically requested all those who would apply my classi- 

 fication to distant parts, to look to two great natural portions 

 only, into which the Silurian system might be expected to 

 divide itself in other countries, viz. " Lower and Upper Si- 

 lurian," the local distinctions in each of which would probably 

 be found to be various in different countries ; whilst the ge- 

 neral distribution of the fauna in each would, I hoped, be 

 proved to harmonize with the physical and zoological arrange- 

 ment of one great natural system. It is in this point of 

 view that the Silurian system has since been applied to va- 

 rious parts of Europe and North America, and has been 

 found to stand the test. But however the smaller subdi- 

 visions of distant countries may differ from each other, I 

 would here remind geologists, that in these ancient rocks, as 

 Avell as in those of secondary age, similar types of organic 

 life frequently occur on the same horizon in distant lands, 

 when similar mineral conditions are repeated. Thus, in the 

 lowest fossilliferous schists of Ginetz and Skrey, we are re- 

 minded of the Llandeilo flags and schists of England, and of 

 the Alum-Slates of Sweden, by the development of large Tri- 

 lobites, and the genus Battus, which, together with OrthidjB 

 and Cystidete, peculiarly mark these deposits. In the over- 

 lying quartzose rocks of Bohemia, we cannot fail to be struck 

 with their analogy to the Caradoc sandstone (even in Britain 

 often in a quartz rock) ; and so impressed was I with this 

 resemblance of these siliceous flagstones of Bohemia, which 

 are loaded with Trinuclei, to my British types, that if I had 

 seen these specimens in any cabinet, I would have said that 

 they came from the Caradoc gi'oup of the lower Silurian 

 rocks of my own country. 



Then, as to the upper Silurian, it strikingly resembles the 

 British division of the same age, in being like it eminently 

 characterised by a multitude of chambered shells (Orthoceras, 

 Phroo-moceras, Cyrtoceras, Lituites, &c.), some of the charac- 

 teristic species of which are most abundant in the very heart 

 of this upper division in England ; viz. in the shale between 

 the Ludlow and Wenlock rocks. Again, the middle group of 

 the upper division of Prague contains large Pentamenes, one 

 of which is undistinguishablc in extenial form from the pen- 



