MERfAN ON PEA-IRON-ORE. 



23 



All the more important families of the Coal- formation, with the 

 exception of the Cycadeoi and Palmce, which are rare even in that 

 formation, are here represented. Hence it necessarily follows, as 

 Brongniart has also maintained, that in the long period, from the 

 first appearance of vegetation on the earth to the Red Sandstone 

 overlying the Coal, no real change of the vegetation is observable in 

 the different strata. 



Whether the successional development of plants, here adduced as 

 self-evident, is to be further confirmed, the future will show. For 

 my part, I cannot doubt it. Sharpe and Bunburv find in Portugal 

 extensive coal-beds with land-plants accompanied by Silurian fossils. 

 But this requires further investigation. [T. R. J.] 



Coal-beds of the Larzac. By M. Rouville. 



[Acad. Scien. Montpellier, Nov. 1849 ; and Leonhard u. Bronn's Jahrb. f. Min. 



1851, p. 466.] 



The Larzac belongs to the numerous plateaux, known as the 

 Cousses, which stretch north and south from Espalion (Aveyron) to 

 Clarmont (Herault). These plateaux generally consist of a hori- 

 zontally-bedded limestone, cut up by fissures and valleys, in which 

 the towns of Milhau, Mende, &c. stand. In ascending from Lodeve 

 to Mont Caylar, the Banter Sandstone of Soubis is first traversed, 

 then a dolomitic bed, which represents the white lias of the English 

 geologists or the infra-lias of Leymerie. On this lie the Fucoid- 

 marls noticed by Dumas. Next follows another dolomitic deposit ; 

 the Oxfordian limestone and the Coral-rag, but slightly developed, 

 here predominate. The Plateau de la Cavalerie comprises four or five 

 groups of carboniferous deposits (La Cavalerie, La Liquille Ceral, 

 Saint Georges de Lusen9on) which are situated on the Oohte with 

 Fuci. There are two kinds of coal, only one of which — the glance- 

 coal — is used in the forges. The organic remains that have been 

 found belong to the genera Cyclas, Paludina, Mytilus, and Cyi^ena. 

 There are no traces of plant-remains. This deposit of coal is of much 

 interest, as it appears to indicate a true Weald-formation [Weald- 

 gebilde] in the midst of the Jurassic series. [T. R. J.] 



On Pea-Iron-Ore. By P. Merian. 



[Bericht Verhandl. Naturf. Gesellsch. Basel, 1851, ix. pp. 44-47.] 



Alexander Brongniart's view, that the Pea-ore [Bohn-erz] of 

 this neighbourhood (Basle) belongs to the Tertiary age is clearly incor- 

 rect ; since, wherever the beds of pea-ore occur in their original posi- 

 tion, they are always covered by the Tertiary deposits. Besides, the 

 geographical extension of the pea-ore beds on the western declivity 

 of the Black Forest between Basle and Freyburg supports the view 



