b GEOLOGICAL MEMOIRS. 



there are associated with them mimerous fossils characteristic of 

 the earlier period of the third fauna, whilst the Crustaceans and 

 Cephalopods appertaining to the latter part of that fauna are entirely 

 wanting. In the Harz, however, the presence of Ctenacanthus among 

 fishes and of Dalmanites and Bronteus among Trilobites, associated 

 with forms of Devonian type, renders it probable that the limestones 

 of Magdesprung represent an epoch near those represented by stages 

 G and H (p. 266). 



In the IJnited States of America the closest analogy to the fauna 

 of G and H is found in the Upper Helderberg group (especially in the 

 State of iN'ew York), which, by its Gasteropods, Acephala, and Bra- 

 chiopods, presents clearer connexions with the Devonian fauna of 

 Europe than do the similar zones of Bohemia. 



With respect to the connexions between these two higher zones 

 and the Devonian system, after passing in review all the evidence to 

 be derived from organic remains, the author arrives at the conclusion 

 that generally they are not more directly united to the Devonian 

 fauna than are the higher zones of any of the other Silurian countries 

 where the third fauna has a less vertical development, and is even 

 reduced to its first phase ; for if in Bohemia they contain the genus 

 Goniatites, which is not met with elsewhere, in the former they contain 

 several genera of fishes, and of other types, as Galceola, Grammy sia, 

 Pleurodictyum, &c., which occupj?- a distinguished rank among Devo- 

 nian fossils, and which are completely wanting in the Bohemian 

 Silurian rocks. And, with reference to specific connexion, the two 

 upper stages in Bohemia contain fewer species identical with Devo- 

 nian forms, and fewer representative forms, than do the inferior 

 stages E and E. In fact his researches lead him to the apparently 

 paradoxical conclusion that the two highest members of his third fauna 

 present less strong connexions with the Devonian system than do 

 those which immediately precede them. 



Taken, therefore, from a palaeontological point of view stages G 

 and H preserve completely a Silurian character, and are not united 

 to the Devonian system except by those usual hnks which announce 

 the approach of a succeeding period. [II. B. H.] 



Elements of Chemical and Physical Geology. By Dr. Gustav 

 BiscHOE, Eor.Mem.G.S.,&c. Yol. II. Second Edition*. 



[Lehrbuch der chemischen und physical! schen Geologie. Von Dr. Gustav 

 Bischof, For. Mem. G.S. Zweite ganzlich mngearbeitete Auflage, Band II. 

 Bonn, 1864.] 



In this volume of the new edition of Dr. Bischofs well-known 

 * Elements of Chemical and Physical Geology,' the whole of the material 

 of the former edition has been re-arranged, more especially with a view 

 to condensation, but, as a large amount of additional matter has been 

 incorporated, the dimensions of the work are still very great, the 



* Volume i. of this edition was noticed in Quart. Journ. Geol. Soc. toI. xx. 

 Part II. Miscel. p. 13. 



