30 GEOLOGICAL MEMOIRS. 



fined basin whose shape is oval, the longer axis having a N.E. and 

 S.W. direction, whose respective extremities are near Auval and not 

 far from Klattau. The length of this axis is about eighty-two En- 

 glish miles : the breadth of the basin varies, but is nowhere greater 

 than seventy English miles, and is generally much less, especially to- 

 wards the N.E., where it is partly covered by the Quadersandstein, 

 Planer-kalk, &c. Elsewhere, for about four-fifths of the whole cir- 

 cumference, the palaeozoic basin reposes on granites and gneiss, 

 which often seem to alternate and be mixed up with metamorphic 

 rocks. 



In this extensive basin there are a number of deposits of diff'erent 

 ages, also basin-shaped, and so arranged that their relations can be 

 well- studied. 



The palaeozoic formations of the centre of Bohemia present a 

 complete series of all the principal subdivisions indicated in the con- 

 temporaneous rocks of other countries. The series being here com- 

 plete, the natural divisions seem manifest even before they have been 

 made out by a consideration of the fossil evidence. 



The author adopts three chief divisions corresponding to three 

 very different kinds of deposits. Palseontological considerations have 

 induced him to make yet further subdivisions or groups. They are 

 thus classed in order of superposition. 



3. Upper Division. — Including a mass of calcareous beds almost 

 uninterrupted in appearance, but of which the great difi'erence of 

 dominant fossil types requires a subdivision into three distinct groups. 



2. Middle Division. — Including the protozoic formations di- 

 vided into two groups, of which the faunas are quite distinct. 



1. Lower Division. — Including all the Azoic formations, and 

 subdivided into two groups. 



I. Lower Division. 



These rocks appear wherever the exterior margin of the palaeozoic 

 basin is recognized. 



Group A.— This lowest group includes all the crystalline or semi- 

 crystalline rocks generally designated as metamorphic ; such rocks 

 are very variable in distant spots. They repose on granite and gneiss, 

 and the author states that he intends to give in detail at a future 

 time, some facts which he has observed with regard to them, which 

 appear to him to settle the question of metamorphism. 



Group B. — This upper group consists of masses which are not 

 crystalline, such as the grauwackes of Przibram, manifestly from their 

 structure of marine origin ; many rich metalliferous veins enrich 

 this formation, especially near Przibram. 



Of this age are probably the argillaceous schists, on the opposite 

 or north-western side of the basin, as well as those which underlie the 

 coal-basins of Pilsen and Radnitz. Several pyritous or alum schists 

 are included also in the series, apparently in the upper portion. No 

 organic contents have yet been found in these rocks, and the author 

 believes that they belong to the group called Azoic, below the limits 

 of organic existence. 



