Reviews — Silurian Rocks of Bohemia. 367 



Pupa, and Acliatina ; bones of the Mastodon have also been dis- 

 covered in it. 



The Yellow Loam overlies the Loess, where that exists, and else- 

 where the Orange Sand ; its average thickness is from 5 to 10 feet, 

 and its characters vary more or less in accordance with those of the 

 underlying material, which enters into its composition, and therefore 

 testifies to a certain amount of denuding action. 



The Hummocks, or Second Bottoms, as the newest beds are called, 

 form part of the valleys of all the larger streams of the state, and 

 are in general most extensive where the material of the adjoining 

 uplands was most easily denuded, so as to permit the excavation of 

 deep valleys ; while, where that material resisted denudation, the 

 contraction of the valley, and consequent, greater swiftness of the 

 stream, have either prevented the formation of these deposits, or 

 caused their subsequent removal. 



3. Note on the Presence of Low Forms of Vegetation ffilamentous 

 ConfervceJ in tlie hot and saline ivaters of California, by Professor W. 

 H. Brewer. — -The waters contain a variety of salts in solution, prin- 

 cipally sulphates of iron and alumina. The highest temperature in 

 which the vegetation grew was about 200° F. 



H. B. W. 



ZR-ZBAT-IZB^VsrS. 



L SiLUEIAN EOCKS OF BoHEMIA. 



By M. J. Barrande. 

 [Defense des Colonies. III. Etude generale sur nos Etage G-H. ; avec 



APPLICATION SPECIALE AUX ENVIRONS DE HlUBOcEP, NEAR PrAGUE. Par 



Joachim Barrande. With a coloured Map and Plate of Sections. 8vo. Paris 

 and Prague, 1865]. 



MOEE than twenty-five years ago M. Barrande began a careful 

 search in the Palgeozoic strata near Prague for fossils, whereby 

 to learn their exact relations one with another, and with like strata 

 elsewhere. He worked on a large scale, employing native workmen 

 to quarry the rocks and collect every fossil and fragment of fossil, 

 keeping special note of the layer in which it occurred. Before long 

 this steady and perfect examination of every bed enabled M. Bar- 

 rande to determine several groups of so-called Silurian strata, round 

 about Prague, arranged in a great basin or trough, and divisible into 

 eight successive formations or stages. Three great and distinctive 

 assemblages of animal forms (faimas) characterize the fossiliferous 

 part of these stages. Beneath all is the old gneiss, the marble in 

 which has lately yielded Eozodn to Hochstetter and Gumbel. 

 Stages A and B, as yet unfossilliferous, are the Przibram and other 

 Schists, and may be equivalent to the ^' Cambrian " of Britain, or 

 the " Huronian " of Canada. Stage C, or the Grinetz beds, is cha- 

 racterized by the "Primordial Fauna" of Barrande, and is analogous 



