older Deposits of the North of Germany and Belgium. 261 



Though we do not wish to fatigue our readers by emptying our note-books of 

 their details, yet having made so many traverses, we may advert to some additional 

 illustrative districts. The Aggerthal, for example, along great part of which the 

 new chausse'e from Cologne to Berlin passes, lays open a considerable variety of 

 beds of arenaceous grauwacke, schist, hard flagstone, and dull grey-coloured lime- 

 stone. The limestone, occurring in large concretionary masses, is often loaded with 

 corals. The shales which alternate with limestones are sometimes charged with 

 the same shells that characterize the Silurian grauwacke in the country which 

 surrounds the Eifel on the left bank of the Rhine ; viz. the same small species of 

 Orthis which occurs at Priim ; the small variety of the Terebratula aspera, so cha- 

 racteristic of the Silurian system (T. affinis, Sow.) ; a species of small spinose 

 Producta, identical with a shell found in the beds under the Eifel limestone at 

 Cronenburgh and at Miinster Eifel ; and two Spirifers common in the same tract. 

 (See PI. XXIII. figs. 12 and 13.) 



The above species, with the coral Favosites polymorpha, are singularly abundant 

 at Meinershagen and to the north of Gummersbach. Near Engelskirchen the flag- 

 stones, sometimes passing into calciferous grits, are largely quarried, and contain 

 the Orthis, &c. 



Between Aggerthal and the Westphalian coal-field, we met with many fossils, 

 especially in the grauwacke north of Marienheide. They consist of several 

 new forms, including the cast of a very remarkable, large Terebratula. And 

 we ought not to omit the fossiliferous limestones, alternating with schist and 

 sandstone, which are seen in vertical and highly inclined strata on the banks 

 of the Lenne above Altena : at Esel for example, where we detected the Caly- 

 mene macrophthalma, with flattened Orthoceratites in impure, black, slaty lime- 

 stone ; and also near Neunrade, where the beds teem with magnificent specimens 

 of corals*. 



many of the details given in his work concerning the age of the igneous rocks of Nassau (which 

 have been much criticised, particularly by M. Stifft), our object being simply to call attention to the 

 above fact. In his geological description of the duchy of Nassau, M. Stifft has not only presented 

 us with a most elaborate mineralogical description of all the rocks of igneous origin, but has also, to 

 some extent, expressed his opinion that the uppermost strata of the region, though called grauwacke 

 by Becher and other previous authors, are, in reality, the equivalents of overlying deposits of the age 

 of those rocks which, in the adjacent countries, support and pass into the carboniferous deposits'. It 

 is to be regretted that he has not drawn this distinction in his map : but notwithstanding this defect, and 

 the entire want of sections, his work is of great merit considering the date of its publication, and is re- 

 plete with many important and curious facts concerning the igneous and altered rocks, mineral ores, and 

 springs of Nassau. 



* This fine section is laid bare by the cuttings of the new road ; and we may here remark, that the 

 best sections we found in Westphalia were along the noble lines of new roads cut by order of the Prus- 

 sian government. 



VOL. VI. SECOND SERIES. 2 M 



