TRANSACTIONS OF THE SECTIONS. 51 



3. The Upper Silurian has afforded land plants only in its upper beds, and only 

 at Gaspe in Lower Canada. The only well-characterized species is PsUopkyton 

 princeps, which is also one of the most common plants in the Devonian. The first 

 known appearance of land plants in America is thus at the same geological period 

 with their first known appearance in Europe. 



4. The Lower Silurian has as yet afforded few land plants. It abounds in ob- 

 jects called fucoids, but the greater part of those are trails of worms, crustaceans 

 and mollusks, rill-marks, shrinkage-cracks, &c. Those that show carbonaceous 

 matter or structure seem to be allied to Northern Alga?. The extent of shallow- 

 water deposits of the Lower Silurian explored in Eastern America without any 

 observance of land plants, would seem to afford at least a presumption against their 

 abundance at that period. 



The author anticipates that the Laurentian will yet afford evidence of at least 

 the existence of Alg;e before the Palaeozoic period. He has prepared for commu- 

 nication to the Geological Society a detailed accoimt of that part of the above succes- 

 sion which relates to the Carboniferous of British America. 



On the Lower Lias of Lyme Regis. By E. C. H. Day. 



On a Head of Hybodus Delabechci. By E. C. H. Day. 



On the History of the Jurassic Seas, as evidenced by the History of the first 

 Liassic Sea. By E. C. H. Day. 



On the Large Prussian Geological Map of the Rhenish Provinces and Wtst- 

 pludia. By Geheimkath H. von Dechen and Prof. E. Eomer. 



M. Geheimrath H. von Decheu, of Bonn, gave a general explanation of the large 

 Geological Map of the Rhenish country, and of the Province of Westphalia, which 

 is chiefly his own work, and which after twenty years of incessant labour has just 

 now been finished. This map embraces one of the most interesting parts of Ger- 

 many. Besides the Devonian strata which occupy the greater part of its area, 

 the highly remarkable volcanic phenomena of the Eifel and of the Laacher See are 

 contained within its limits. 



The whole map was executed by order of the Prussian Government. Its scale is 

 s^ioo- -A certain number of sheets of the map were exhibited in the Section-room. 



Dr. Ferdinand Rbmer, who has taken part in the survey of this map, made some 

 additional remarks on the Devonian strata represented on it. The Devonian rocks 

 of the Rhenish country exhibit the most complete and best developed series of 

 the Devonian system which exist anywhere in Europe. The whole system is here 

 distinctly divided into three main divisions, viz. : — 1. The Coblenz Grauwacke, con- 

 sisting of dark-coloured sandstones and clay-slates of a total thickness of at least 

 10,000 feet. Trilobites of the genus Homalonotus, Spirifer macropterus, Cho- 

 netes sarctnulatua, and several species of the genus Pterinea, are the most charac- 

 teristic organic types. In Devonshire this lowest division of the Devonian rocks 

 on the Rhine is very little developed, or at least very imperfectly known as regards 

 its organic remains. A few fragments of Homalonotus armatus, and of Gryphceus 

 (Plan-acanthus) laciniatus, aud casts of Chonetes sarcinulatus, from Meadsfoot sands, 

 are almost the only documents from which the existence of the Coblenz grauwacke 

 in Devonshire may be inferred. 



2. The Eifel limestone, i. e. a series of limestone beds and calcareous marls which 

 chiefly constitute the several basins in the hilly region called the Eifel, which, 

 surroimded everywhere by the Coblenz grauwacke, appear like islands on a geolo- 

 gical map. This Eifel limestone forms the very centre of the Devonian system, 

 and contains that wonderful variety of fossil shells, Corals and Radiata in a beauti- 

 ful state of preservation, which have made the Eifel a celebrated region to palaeon- 

 tologists. This middle group of the Devonian series on the Rhine is distinctly re- 

 presented in Devonshire. The limestones of Torquay, Plymouth, and other loca- 



4* 



