1854.] 



HAMILTON MAYENCE BASIN. 



269 



appeared to be the produce of calcareous springs. To the north- 

 west of this mass, the beds, which are nearly horizontal, are essentially 

 calcareous, varying considerably in their degrees of hardness, and 



Fig. 10. — Section of the Cerithium Limestoiie (B. 3) with Calc- 



Sinter, between Hochheim and Florsheim. 

 w. 



strata indistinct : Amorphous : Strata distinct : 



calcareous. arenaceous. 



;rata indistii 

 calcareous 



sometimes passing into soft calcareous marl ; while on the east or 

 south-eastern side, they are essentially arenaceous, the stratification, 

 especially at a short distance from the central mass, being more 

 distinct than on the other side. On this eastern side we observed 

 the following features in an ascending order : — 



a. Loose sand, with a few Helices and Perna, from 10 to 20 feet 



thick. 



b. Several bands of concretionary limestone-nodules, running 



through the same greenish sand. 



c. Bands of hard limestone, 6 inches thick, containing numerous 



casts of a small Cerithium. 



d. Two bands, a few inches thick, and three or four feet apart, 



containing Venus incrassata. 



e. Band containing Perna Soldanii. 



On the north-western side the palseontological evidence is less 

 clear, and the stratification is much less regular. Numerous He- 

 lices and Cyclostomata, particularly C. sulcatum, occur in patches here 

 and there, together with Venus incrassata and Perna. The great 

 difference in the lithological character of the two sides of the 

 section may, I think, be accounted for in this way : — if we suppose 

 that a large river, occupying the position of the present Maine, 

 flowed into the lacustrine basin from the Spessart, viz. from the 

 E. or E.S.E., the action of the water on the calcareous spring 

 would cause the calcareous matter to be deposited on the western or 

 further side of the spring, while the matter deposited on the eastern 

 side consisted of the more arenaceous sediment brought down by the 

 river itself. 



Another section further westward, and nearer Hochheim, produced 

 an abundance of small Cerithia, with Mytihis socialis, fragments of 



