1855.] MURCHISON AND MORRIS — THE HARZ. 433 



weeds ; but one large and true land plant has also been found, and 

 has been called by M. Adolf Roemer a Sigillaria. On the whole, 

 these flagstones, which when extracted are occasionally 10 feet by 

 7 feet, reminded us in their aspect of the Scottish Arbroath paving 

 stones, and the so-called Valentia slates of Ireland, both of Devonian 

 age *. 



Plunging distinctly at Q^° to the S.E., these strata are followed 

 by others slightly differing in mineral characters, but which, being 

 little cut into, are not so well known as those at the works of Mag- 

 desprung ; but the apparent ascending order is unambiguous in 

 exposing a seemingly conformable succession upwards, with a dip 

 to the S.E. for about half a mile, until a band of limestone {b) 

 is reached, in which the numerous fossils have been found which 

 constitute the Silurian collection of M. Bischof. This limestone, 

 from 30 to 40 feet thick, is hard and crystalline, of dark grey 

 colour with white veins, rough to the touch, and is separated into a 

 lower and upper portion by a thin course of schist. In another layer 

 of schist which immediately overlies the limestone, we detected 

 innumerable small Tentaculites-f. In the mass of the limestone 

 M. Bischof collected numerous organic remains, of which we will 

 only now allude to those that best prove the rock to be of Upper 

 Silurian age : some of them we now exhibit. Thus, among several 

 genera of Trilobites we recognized Calymene, Acidaspis, Lichas, and 

 Cheirurus, common in Upper Silurian and unknown in Devonian 

 rocks. These, however, are associated with Phacops and Bronteus, 

 which chiefly prevail in the Devonian. Among the mollusca are 

 Leptcena transversalis, and L. borealis and L. robiistus (Barr.), 

 Nerita haliotis, Orbicula Forbesii, Acroculia depressa (^haliotis, Sil. 

 var.), Orthis alata, together with the corals Favosites Gothlandica 

 and CystiphyUiim turbinatum. Again, whilst the above are un- 

 questionably Silurian, Terebratula princeps, and some other forms, 

 indicate a close approach to the Devonian. 



These fossiliferous flagstones, schists, and limestone are sur- 

 mounted by a coarser grauwacke approaching to gritty sandstone, 



* In a memoir recently published in the * Palseontographica ' of Dunker and 

 Von Meyer (Cassel, 1855), M. Adolf Roemer, in further describing the structure 

 of the Harz, has given a map of the tract around Elbingerode, which repre- 

 sents a considerable band of Silurian grauwacke with an included limestone along 

 the north flank of the chain, S. of Wernigerode, followed by various subdivisions 

 of the Devonian series from the Spirifer-sandstone through the Wissenbach schists, 

 Stringocephalus-limestone, grauwacke, schist, and schaalstein to the Iberger or 

 Upper Devonian limestone. 



In the short notices prefixed to the descriptions of the fossils, the author has 

 misunderstood the opinions I formed as to the age of the limestones of the 

 Schneckenberg near Harzgerode, and of the flagstones with plants near Magde- 

 sprung. "With regard to the former, I did not see sufficient fossil evidence to 

 enable me to come to a decisive opinion, though it is probable, judging from 

 some of the forms described by Roemer, that the rock may be Upper Silurian. 



The age of the flagstones of Magdesprung with plants has been regarded by me 

 in the text as Devonian, — and not Silurian, as stated by Roemer. The recent- dis- 

 coveries of large land-plants low down in the rocks of Devonian age in Caithness 

 would seem to sustain this suggestion. — R. I. M., Oct. 12, 1855. 



t Resembling T. l<Bvis of the Devonian rocks, but probably another species. 



