older Deposits of the North of Germany and Belgium. 283 



remains. In these rocks were one or two species of Orthis, two large species 

 of Delthyris, and the singular coral Pleurodictyum problematicum ; which fossils 

 also abound in the formations under the Eifel limestone ; and are commonly 

 found on the banks of the Ahr, the Rhine, and the Lahn, associated with the 

 Homalonoti, and other characteristic Silurian types. Thus were our previous 

 conclusions respecting the age of the mineral masses composing the Hundsriick 

 and the Taunus, confirmed by the additional evidence of the fossils. It is indeed 

 true that organic remains are very rare within the limits of these chains ; but 

 our only surprise was that any traces of organic forms should have been left 

 among rocks so greatly mineralized*. 



As general conclusions from this and the preceding part, we may state : — 



1. That, considered on a broad scale, the successive natural groups of strata, 

 and the successive natural groups of fossils are in approximate accordance. 



2. That as the broad areas of the physical groups of strata are ill defined, so 

 also are the boundaries of the fossil groups ill defined, and pass into one another. 



3. That as there are no great mineralogical interruptions of the deposits, producing 

 a discontinuity or want of conformity among the masses, so also there seems to be 

 no want of continuity among the groups of the great Palaeozoic series of animal 

 forms. If the extreme terms be compared together, every object is dissimilar: 

 but when the proximate groups are put side by side, there are many points of re- 

 semblance, and many of specific agreement. These conclusions are not offered as 

 an hypothesis, but appear to us as legitimate inferences from the facts we have 

 had before us during the compilation of this paper. 



PART III. — Structure and Formations of the Hartz. — Upper Franconia, 8fc. 



(Plate XXIII. Sect. 15, 16, 17 and 18.) 



GENERAL STRUCTURE OF THE HARTZ. 



Before we proceed to notice the formations of the chain of the Hartz, it seems 

 expedient to give a brief sketch of its structure, which is, we believe, not well 

 understood by the generality of British geologists. In English works, published 

 not more than twenty years since, and professing to give some account of this 

 region, the granite of the Brocken was placed in the geological centre ; and all 

 the stratified formations were delineated as mantling round it, and dipping from it 

 in most regular order, beginning with the oldest slates at a high angle of inclination, 



• See PI. XXni. fig. 9. 



