the Devonian Hocks of Moravia, 69 



verj best and most interesting monographs which has ever 

 enriched geological science.* 



Referring your I'eaders to the annexed transverse section 

 across the broadest part of this Bohemian basin which con- 

 tains fossils, and excluding from our view those inferior 

 rocks in which no fossils have been discovered, it may be 

 stated that, so defined, the Silurian rocks there extend from 

 NE. to SW., through a distance of about 10 German miles, 

 and have a maximum breadth of about 2>h miles from NW. 

 to SE. This direction of the major ellipse of the Bohemian 

 basin is the same as that of the typical Silurian rocks of 

 Britain, and, like the British type, consists of two great di- 

 visions. The outer zone, representing the lower Silurian 

 rocks, and composed of schists, shale, conglomerate, and 

 quartzose rock, encircles and dips under an ellipsoid of lime- 

 stone and shale, which represents the upper Silurian. The 

 external zone, or that in whicli the oldest fossils have been 

 found, is marked in its lowest stage by an earthy schist of 

 greyish and dull green colours, [c of section, Plate II.) which is, 

 in truth, a very good representative of the " mudstones" and 

 " rotch" of the Silurian Regions, like which, it is devoid of any 

 distinct slaty cleavage. At the places where we examined 

 this rock, (Ginetz on the one. side, and Skrey on the other side 

 of the basin) it is scarcely to be distinguished from other 

 schists (b) which underlie it quite conformably, and are in- 

 tercalated in quartzose and conglomerate grey wacke, similar 

 to that which at Skrey is seen to overlie the fossil stratum 

 (c.) These underlying rocks, {a and b) which M. Barande 

 has very properly distinguished from the overlying by their 



* Since M. IJaraiule issued his " Notice Preliininaire," and gave tlie first 

 correct general sketch of the Silurian basin of Bohemia, with an account of 

 115 Kpecics of trilobites, SIM. Ilaule and Corda liave published a prodromus of a 

 publication on the Uohemian trilobites, in which I regret to observe that no 

 allusion is made to the meritorious discoveries of Jl. liarande. I leave to 

 palicontologifts to decide eventually on the value of a work in which the au- 

 t'lors profess to describe 329 species of Crustaceans ! but, on the part of my 

 frimds and self, I must protest against tlieir geological view, that all these di- 

 versified and finely laminated strata were contemporaneous or nearly so, and 

 cannot be separated into groups of succesbivo ages. 



