Geological Society. 407 



occasionally presenting obscure impressions of plants, and casts of a 

 large Homalonotus, of a Silurian species. Thie sequence, deter- 

 mined more by the symmetrical position of the great mineral masses 

 than by direct superposition, as seen in vertical sections, gradually 

 passes into rocks of a more decidedly slaty structure, and almost 

 without fossils. Passing to the right bank of the Moselle, and in 

 the same way making traverses through the chain of the Hunds- 

 ruck (which is elevated on the line of strike, i. e. east-north-east), 

 they again had an ascending series, and thence concluded that the 

 whole chain w as only a portion of the gi-eat system under the Eifel 

 limestone in an altered form. The Silurian fossils discovered among 

 the crystalline quartzites and schists of the chain (e. g. one or two 

 species of Orthis, a large winged Delthyris, &c.), confirmed this 

 view. Hence also the chain of the Taunus, which is the physical 

 prolongation of the Hundsruck, must be referred to a similar place 

 in the general series ; a conclusion at which the authors also arrived 

 from an examination of the sections on the right bank of the Rhine, 

 though obscured by the enormous development of masses of con- 

 temporaneous trap (^Schaalstein). 



The authors then give some details respecting the trappean and 

 volcanic rocks on both banks of the Rhine, and conclude, that the 

 quartzite and chlorite slates, &c. of the Hundsruck and Taunus are 

 but altered fonns of a great Silurian group under the Eifel lime- 

 stone ; and that the causes which at an ancient epoch dislocated, 

 contorted, and minei-alized the strata, have perhaps not yet entirely 

 ceased, and that the hot springs of Wisbaden and bubbling fountains 

 of Nassau, may be referred to their last expiring efforts. 



On a review of all the facts stated in this and the preceding Part 

 of their communication, the authors conclude, (1.) That from the 

 carboniferous deposits of Westphalia and Belgium, to the lowest 

 fossiliferous deposits of the Rhenish provinces, there is a great and 

 uninterrupted series of formations, which are in general accordance 

 with the British series, though the subordinate groups do not admit 

 of direct comparison ; (2.) That, considered in a broad point of 

 view, the natural successive groups of strata and the natural suc- 

 cessive groups of fossils, are in general accordance ; but as the 

 boundaries of the physical groups are ill defined, so also the bound- 

 aries of the fossil groups are ill defined, and pass into or overlap one 

 another ; (3.) That as there are no great mineralogical interruptions, 

 producing a discontinuity and a want of conformity among the de- 

 posits, so also there seems to be no want of continuity among the 

 groups of the great palaeozoic series of animal forms. If the ex- 

 treme terms be compared together, all the objects are dissimilar ; 

 but if the proximate fossil groups be put side by side, there are 

 many points of resemblance, and many of specific agreement ; (4.) 

 That the Devonian system is, therefore, a natural system, not merely 

 made out, as in England, l)y a plausible interpretation of fossil evi- 

 dence, l)ut defined, in the Rhenish provinces, both by its group of 

 fossils aild its place in a true descending section. And as the old 

 red sandstone of Herefordshire passes on the one hand into the car- 



