290 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 22, 



The collection in the museum at Berne was not, when I visited it, 

 completely arranged, nor were the localities given with such a degree 

 of accuracy as to show from what portion of the Molasse the large 

 collection of Mollusca, classed generally as belonging to it, was 

 derived. The principal features which struck me were the great 

 preponderance of Bivalves, and the rather more recent fades of the 

 whole collection. It is well known that this formation is very 

 generally extended over the great central valley of Switzerland, 

 between the Alps and the Jura ; it is to be traced in almost all the 

 valleys of the Jura, forming terraces on the sides of the hills, or 

 occupying the bottoms ; and it also occurs in most of the valleys on 

 the northern flank of the Jura, opening into the valley of the Rhine 

 below Basle t ; and a few miles from Basle, north of the Rhine, at 

 Lorrach in Baden, is one of the best localities, according to Prof. 

 Merian, for studying the Molasse formation, where it occurs as a 

 kind of calcareous rock (formerly extensively quarried), and overlaid 

 by freshwater limestone. Indeed it is said that this formation may 

 be traced all round the basin of the ancient sea, and along the hills 

 of Alsace, where a large species of Ostrea is found attached to the 

 Jurassic limestone, on which it once grew when this limestone formed 

 the cliffs rising up from the shore of the tertiary sea. 



When we look at the physical connection between the formations 

 of the Mayence basin and the older rocks against which they are de- 

 posited, it is evident that the hills which constitute the western side 

 of the Valley of the Upper Rhine, forming the mountains of the 

 Haardt and the Vosges, had already assumed in a great measure 

 their present forms and characteristic outlines before the deposition 

 of the tertiary beds. On the western side of the Rhine the tertiary 



reached England, giving the results hitherto ohtained respecting the fossil con- 

 tents of the Molasse. In general, however, the specimens are so imperfectly pre- 

 served, that it is difficult to make out the species accuratelj'. Yet, from the list 

 published by Prof. Studer, it is remarkable what a large proportion of the Mollusca 

 of the older Molasse of Basle, Porrentruy, &c., are identical with the fossils of 

 the Mayence basin. After describing these Molasse beds, and hesitating as to 

 whether they should be referred to the Eocene or Miocene groups, showing that 

 in some places they approach an eocene, in others a miocene/acies. Prof. Studer 

 observes that there is a remai-kable analogy, which might almost be called identity, 

 between the North Jura marine tertiary formation and that of the Mayence basin ; 

 not only in the rock itself, but in its organic remains, singularly like those of the 

 Mayence basin ; and, although many species are difficult to identify, some of the 

 most characteristic, as Halianassa and Fishes, Ceriihia, Natica gigantea, Panopcsa 

 intermedia, Corbula pisum, Pectunculus crassus, and Ostrea Collinii, are common 

 to both formations. 



t It now appears from Prof. Studer's work, that the Molasse formation must be 

 separated into two cliief divisions : 1. That of the Northern Jura ; 2. That of the 

 Interior or Mittel-land. The former is overlaid by a freshwater formation ; the 

 latter, which assumes a more recent character, is divided into two subdivisions, 

 — the subjurassic and subalpine zones, and lies between two freshwater forma- 

 tions. Of these, the fauna of the Subjurassic zone has considerable resemblance 

 with that of the Marine Molasse of Basle ; while the fauna of the Subalpine zone is 

 compared with that of Bordeaux, Vienna, and the Subapennine formation of the 

 North of Italy. 



