Ch. XIV.] SHELLS IN MIOCENE STRATA. 1Y9 



Island Sylt, and at Bersenbruck north of Osnabiiick, in Westphalia, 

 where it was first discovered by F. Romer. It is also said to occur at 

 Bocholt, and other points in Westphalia ; on the borders of Holland ; 

 also at Crefeld and Dusseldorf. Not having visited these localities, I can 

 offer no opinion as to the agreement in age of the several deposits here 

 enumerated. 



Vienna basin. — In South Gcrm.any the general resemblance of the 

 shells of the Vienna tertiary basin with those of the fahms of Touraine 

 has long been acknowledged. In Dr. Homes' excellent work, recently 

 commenced, on the fossil mollusca of that formation, we see figures of 

 many shells of the genus Conus, some of large size, clearly of the same 

 species as those found in the falunian sands of Touraine. M. Alcide 

 d'Orbigny has also shown that the foraminifera of the Vienna basin differ 

 alike from the Eocene and Pliocene species, and agree with those of the 

 faluns, so far as the latter are known. Among the Vienna foraminifera, 

 the genus Amphistegina (fig. 163) is very characteristic, and is supposed 



Fix. 163. 



Amplihtegina JIa-uerina, D'Orb. Vienna, miocene strata. 



by Archiac to take the same place among the foraminifera of the Miocene 

 era, which the Nummulites occupy in the Eocene period. 



The Vienna basin is thought by some geologists to comprise tertiary 

 strata of more than one age, the lowest strata reached in boring Artesian 

 wells being older than the faluns. 



Piedmont. — Switzerland. — To the same Miocene or " falunian" epoch, 

 we may refer a portion of the strata of the Hill of the Superga near 

 Turin in Piedmont,^ as also part of the Molasse of Switzerland, or the 

 greenish sand which fills the great Swiss valley between the Alps and the 

 Jura. At the foot of the Alps it usually takes the form of a conglomerate 

 called provincially " nagelflue," sometimes attaining the truly w^onderful 

 thickness of 6000 and 8000 feet, as in the Riga near Lucerne and in 

 the Speer near W^esen. The lower portion of this molasse is of fi'eshw^ater 

 origin. 



Scotland. — Isle of Mull. — In the sea-cliffs forming the headland of 

 Ardtun on the west coast of Mull, in the Hebrides, several bands of ter- 

 tiary strata containing leaves of dicotyledonous plants were discovered in 

 1851 by the Duke of Argyle.f From his description it appears that 

 there are three leaf-beds, varying in thickness from li to 2l feet, which 

 are interstratified with volcanic tuff and trap, the whole mass being about 

 130 feet in thickness. A sheet of basalt 40 feet thick covers the whole ; 



* See Sig. Giov. Mknelotti's works. \ Quart. GeoL Journ. 1851, p. 89. 



