482 HISTORY OF GEOLOGY AND PALAEONTOLOGY. 



Alpine limestone; above it, dolomite and Cardita strata; then 

 Upper Alpine limestone (Wetterstein), succeeded by Gervillia 

 strata and Lithodendron limestone. Three years later Pichler 

 accepted Richthofen's divisions of Trias, and referred the 

 Wetterstein limestone to its right position below the Cardita 

 or Raibl strata, but advocated the view that the Wetterstein 

 limestone and the Cardita oolites and marls were in interbedded 

 stratigraphical relations with one another. In 1866 and 1867 

 Pichler gave a series of geological sections in which he made it 

 appear that between the Wetterstein Dolomite and the Virgloria 

 limestone there was a thick and diversified complex of arenaceous 

 and argillaceous strata, dolomite beds and nodular limestone, 

 which contained a fauna like that of the Cardita strata, and 

 probably corresponded in North Tyrol to the St. Cassian fauna 

 in South Tyrol. Pichler thus originated the idea that an 

 "Upper Cardita" or "Raibl" series and a "Lower Cardita" 

 or "St. Cassian " series could be distinguished normally above 

 and at the base of Wetterstein limestone, but sometimes inter- 

 stratified with it as equivalent facies. 



About the same time, in 1866, another point was gained in 

 the comparison between Alpine and extra-Alpine areas. Ex- 

 amples of two typical " Raibl " fossils Myophoria Kefersteini 

 and Corbula Rosthorni were discovered by Sandberger in the 

 lead-glance or galena bed of the Franconian "gypsum Keuper." 

 It was thus ascertained that the Alpine Raibl strata were con- 

 temporaneous with the gypsum and marls which immediately 

 succeed the upper limit of the "Lettenkohlen" or Lower Keuper 

 group in the extra-Alpine areas. Careful observations had been 

 made by Fotterle (1856) on the palaeontological sequence of the 

 Raibl strata in their typical development at Raibl ; those were 

 corroborated in 1867 by Suess, who differentiated the Raibl 

 strata into three palaeontological zones: the Lower, composed of 

 black shales with numerous plant and fish remains; the Middle, 

 composed of limestone beds with Myophoria Kefersteini; and the 

 Upper, composed of marly limestone with Myophoria Whateleyi, 

 Ostrea montis caprilis, Pecten filosus and Megalodon casts. 

 Suess applied the name of Torer strata to the upper horizon. 

 Two years later Stur expressed his view that the lower horizon 

 was the equivalent of the Wengen strata. 



In the summers of 1863 and 1864, special survey work in 

 the north-eastern Alps was carried out by the Survey Depart- 

 ment under the direction of Lipold and Stur, and was the 



