Reviews and Notices of Books. 341 



In the last Crioceras Duvallii, which is a form peculiar to the 

 Neocomian group of the Mediterranean area, may perhaps be C. 

 plicatilis of the Speeten clay ; the rest occur in the Neocomian beds 

 of the S.E. of England and of the N.W. of France. In Hanover 

 Mr Eoemer considers that it is represented by the sandstones and 

 conglomerate of Hils. 



The transgressive passage of the Essen group, over and beyond 

 the area occupied by the lower or Neocomian group, serves to 

 indicate the direction in which subsidence was taking place in that 

 quarter during the cretaceous period ; and confirms an opinion 

 expressed by the late Professor Edward Forbes, after his visit to 

 Aix-la-Chapelle in 1852, that the plant-bearing beds, subordinate 

 to the sands of that locality, were the terrestrial equivalents of 

 the older portions of the cretaceous series. 



The second memoir placed at the head of this notice is a de- 

 scription by M. d'Archiac, of a group of strata, of somewhat the 

 same age as those before noticed, and which are well seen near 

 the Baths of Bennes, in the midst of the Cerbieres (Department of 

 the Aude). A very large part of the region which separates West- 

 phalia from the south of France was included in that which 

 formed the terrestrial surface of the time of the cretaceous marine 

 series ; and the memoir in question is interesting, as it adds much 

 to our knowledge respecting the geographical range and distribu- 

 tion of that Fauna, and suggests speculations as to the source or 

 quarter from which portions may have been originally derived. 

 The Cretaceous Fauna of the European area already presents two 

 such distinct assemblages of forms, that geologists are warranted 

 in distinguishing between the Southern or Mediterranean, and the 

 Northern or Germanic province. It is most probable that the 

 southern of these dates back its origin to times long antecedent to 

 the other, so that the area now represented by the departments of 

 the Var, Hautes, and Basses Alpes, was beneath the waters of the 

 cretaceous ocean during a long lapse of time before the more 

 westerly but adjoining area of France became submerged. The 

 fact of this successive depression is well illustrated by M. d'Archiac's 

 memoir ; the cretaceous strata of the Cerbieres rest unconformably 

 on old Palseozoic slates, yet in spite of their vast thickness there is 

 no part which can be considered older then the Gault of England, 

 and as such, it can be clearly identified with the beds of that stage 

 which overlies the older (Neocomian) formation in the three de- 

 partments before named. This agreement, however, is only 

 general : M. d'Archiac remarks, that it is not with the nearest 

 beds of the same age in that part of France that those of Bennes 

 can be compared with reference to their fossil contents, but rather 

 with those of Gosau (Eastern Alps) with the Planer of North 

 Germany, and the sands of Aix-la-Chapelle ; and that, in addition, 



