190 MAYENCE BASIN". [Ch. XV. 



a certain proportion of the fossils being identical in species with Limburg 

 and. Mayence shells. M. Beyrich enumerates several other localities in 

 North Germany, and particularly one at Magdeburg, and several on the 

 Lower Elbe, where beds of the same age appear. 



Mayence basin. — I have already alluded to the elaborate description 

 published by Dr. F. Sandberger of the Mayence tertiary area, which oc- 

 cupies a tract from five to twelve miles in breadth, extending for a great 

 distance along the left bank of the Rhine from Mayence to the neighbor- 

 hood of Manheim, and which is also found to the east, north, and south- 

 west of Frankfort. M. De Koninck, of Liege, first pointed out to me that 

 the purely marine portion of the deposit (the Lower group of Dr. Sand- 

 berger) contained many species of shells common to the Limburg beds 

 near Kleyn Spawen, and to the clay of Rupelmonde, near Antwerp. 

 Among these he mentioned Cassidaria depressa, Tritonium argutum, 

 Brander (T. flandricum, De Koninck), Tornatella simulata, Rostellaria 

 JSowerbyi, Leda Deshayesiana (fig. 167, p. 188), Corbula pisum (fig. 1*70), 

 and Pectunculus terebratularis. 



The marine beds are in some places covered with brackish-water 

 marls containing Cyrence in great numbers, among which Cyrena semis- 

 triata occurs, with Cerithium plicatum, Corbulomya triangula, Mytilus 

 Fanjasii, and other Limburg and Hempstead shells. Perna Soldani, a 

 shell of the upper Eocene or Merignac beds of the Bourdeaux basin, but 

 also a Vienna basin shell, is characteristic both of the marine and brackish 

 series. Two species of Anthracotherium, A. magnum, Cuv., and A. al- 

 saticum, are met with in the same deposits. 



The upper portion of this Mayence series has at its base a limestone 

 full of Cerithia and land-shells ; among which Cerithium plicatum before 

 mentioned, and another Limburg shell, Venus incrassata, Sow., a fossil 

 common to the Headon or Middle Eocene of England, are met with ; alsc 

 Neritina concava (fig. 194), a Middle Eocene shell, and Rhinoceros in- 

 cisivus y the oldest form of that genus, and called by Kaup Acerotherium. 

 Next above is a limestone, in which Littorinella or Paludina inflata is a 

 very common fossil, with others of the same genus. One of these, very 

 nearly resembling the recent Littorinella ulva, is found through- 

 out this basin. These shells are like grains of rice in size, and Flg ' 16s " 

 are often in such quantity as to form entire beds of marl and 

 limestone, in stratified masses from fifteen to thirty feet in 

 thickness, just as in the Baltic modern accumulations several 

 feet thick of the Littorinella ulva are spread far and wide over Paludina, 



* , Mayence. 



the bottom of the sea. In the same beds, several species of 

 Dreissena abound, a form common to the Headon or Middle Eocene beds 

 of the Isle of Wight, as well as to the existing seas. On the whole, I am 

 not satisfied that this fauna diverges from the Limburg type towards that 

 of the faluns as much as Dr. Sandberger believes. Among the Mammalia, 

 we find Hippoihcrium gracile, Acerotherium (or Rhinoceros) incisivum, 

 Paleomeryx, Chalicomys, &c. Lastly, the Eppelsheim sand overlies the 

 whole, containing Deinotherium giganteum, and some other true Miocene 



