160 Reviews. 



a natural boundary to the south. The Hartz and other mountain 

 districts, which rise more or less abruptly from this northern 

 plain, mark with more or less exactness the limits of the ancient 

 ocean. Alternations of marine and fresh-water deposits are no 

 where met with, nor do any of those combinations of organic 

 forms occur, which are characteristic of brackish waters. This 

 ancient tertiary sea was permanently shut off from those fresh- 

 water basins, which in the interior of Germany formed extensive 

 and perhaps contemporary deposits. The marine tertiary forma- 

 tions, which extend through the countries watered by the Weser as 

 far as Gottingen and Cassel, are a southern prolongation of this 

 North German tertiary deposit, and must be considered as sepa- 

 rated from the north-eastern prolongations of the Mayence basin, 

 which is characterized by its peculiar composition, and the abnor- 

 mal development of its fauna. 



We cannot state thus generally the views of Professor Beyrich 

 without adding one or two remarks, modifying, in some degree, the 

 universality of the expressions. When Professor Beyrich states 

 that there is no alternation of marine and fresh-water deposits, he 

 surely cannot have overlooked the fact that these marine forma- 

 tions almost everywhere overlie the brown coal, and that although 

 no animal remains have been found in this brown coal, it must be 

 looked upon as a fresh- water deposit formed in vast lagoons or 

 swamps probably at no great elevation above the then level of the 

 ocean, and derived from the decay of fresh-water vegetable matter. 

 In the next place it appears to us that in the present state of our 

 knowledge, it is somewhat arbitrary to attempt on the one hand 

 to connect the tertiary beds of Cassel, Biinde, Gottingen, &c, with 

 those of North Germany, from which they are separated by moun- 

 tain ranges of considerable elevation, and on the other to cut off 

 these same Cassel tertiaries from the North Eastern prolonga- 

 tions of the Mayence Basin with which the physical, and, to a certain 

 extent also, the mineralogical connection appears to have been both 

 natural and continuous. 



The author then proceeds to show the importance of institut- 

 ing a comparison between the tertiaries of Belgium and those of 

 North Germany, observing that, although the time is not yet come 

 for the complete development of this parallelism, there are certain 

 established points of connection which must not be lost sight of. 



After explaining Dumont's five systems (Landenien, Ypresien, 

 Panisilien, Bruxellien, and Laekenien), which, taken together, are 

 the equivalents of the Paris Eocene formations up to the sand of 

 Beauchamp, and of those of England up to the Barton clay, he 

 observes : — " Hitherto we know of no fossils from any part of the 

 North of Germany which positively prove the existence of tertiary 

 deposits of so great an age. The oldest North German tertiary 

 Fauna, viz., that of what I have called the Magdeburg Sands 



