ANNIVERSARY ADDRESS OF THE PRESIDENT. IxV 



gical Institute. He observes, however, that five of the most charac- 

 teristic forms, viz. Ammonites Aon (Miinst.), A. Riippelli (Klipst.), 

 A. Gaytani (Khpst.), A. Johannis-Aiistrice (Klipst.), and A. larhas 

 (Miinst.), all occur in the S. Casciano strata, which consequently, 

 notwithstanding great lithological differences, may be safely paralleled 

 with the Hallstadt beds. 



The author then proceeds to state that the true position of the 

 Hallstadt limestone is now clearly made out to be between the lowest 

 Liassic group (to which he supposes the Dachstein limestone to be- 

 long) and the Trias, — and that the fossils contained in it do not afford 

 sufficient evidence to place it with either of these groups, as no spe- 

 cies peculiar to it has yet been found beyond the region of the Alps ; 

 nevertheless its intimate connexion with the Guttenstein limestone is 

 a fair indication that it should be grouped with the Trias. He con- 

 siders it, however, to be a still more difficult question to decide whether 

 the dolomites which occur extensively beneath the Dachstein lime- 

 stone are Triassic or Liassic. Before leaving the Triassic group, the 

 author states that his present object has been to establish the correct 

 parallelism between the formations of the Northern and those of the 

 Southern Alps belonging to the Trias. Without going into detail on 

 the subject, he briefly proceeds to disprove the arguments of M, 

 Klipstein on the one hand, who wishes to place the San Casciano 

 beds in the Middle Jura, and, on the other hand, those of M. Eich- 

 wald, who claims for them a much more ancient position, referring 

 the Neptunian formation of Southern Tyrol to the Mountain Lime- 

 stone. He observes, in reference to this question, that the San 

 Casciano and Hallstadt beds are not to be considered as exact equi- 

 valents of the true Muschelkalk, but as a more recent portion of 

 the Triassic group deposited above it. 



The author next proceeds to describe the Liassic group, the lowest 

 member of which he considers to be the Dachstein Limestone, so 

 called from its constituting the principal portion of the Dachstein 

 Mountains. Y/ith these are associated the Stahrenberg strata. Above 

 these are the Kossen beds, the Gresten beds, and then, constituting 

 the Upper Lias formation, the Adneth and Hierlatz beds. The only 

 one of these formations to which I shall here allude is the Dachstein 

 Limestone. This is described as frequently immediately overlying 

 the Werfen or Guttenstein beds ; sometimes it is deposited on dolo- 

 mite, or united with it above the Hallstadt beds ; and sometimes it 

 rests on the Hallstadt beds themselves. 



Amongst the fossils found in the Dachstein Limestone, Megalodori 

 triqueter of Wulfen, also called M. scutatus, is by far the most 

 abundant. It is found throughout the whole bed, and has been 

 called the Dachstein bivalve, and is so peculiar to this bed as to 

 throw some doubt on M. von Hauer's generalization that the Kossen 

 beds which immediately overlie the Dachstein, and contain a large 

 proportion of genuine Liassic fossils, are to be considered as forming 

 with it only one formation, notwithstanding their obvious petrogra- 

 phical differences. This Megalodon triqueter^ which occurs univer- 

 sally throughout the Dachstein Limestone, has only been found 



