436 



ST. CASSIAN BEDS, UPPER TRIASSIO. 



[Ch. XXIL 



part of the Keuper or Upper Trias ; but whether the "Werfen sand- 

 stone, No. 4, should form part of the same series, or, as Yon Hauer 

 inclines to believe, should be classed as the equivalent of " the' Bun- 

 ter or Lower Trias," is still undetermined. The absence of well- 

 characterized Muschelkalk fossils in the Austrian Alps renders this 

 point very difficult to decide. Rich deposits of salt, associated with 

 the Werfen beds, have inclined some geologists to presume that they 

 belong to the Upper Trias. Should they be classed as " Bunter," the 

 Guttenstein limestone would then correspond in position with the 

 Muschelkalk, but no Muschelkalk fossils have ever been met with in 

 it or in the Werfen. 



Among the 800 species of fossils of the Hallstadt and St. Cassian 

 beds, many are still undescribed ; some are of new and peculiar 

 genera, as Scoliostoma, fig. 467, Platystoma, fig. 468, among the 

 Gasteropoda ; and ITonincMa, fig. 469, among the Brachiopoda. 



Fig. 467. 



Fie'. 



Platystoma Suessii, 



Hoernes. 



From Hallstadt. 



ScoUostoma, St. Oassian. 



Fig. 469. 



KonincMa Zeonhardi, Wissmann. 

 a. Dorsal view, natural size. 

 &. Ventral view, part of the converse ventral valve removed to show the interior of 



dorsal valve and its vascular impressions. One of the spiral processes is seen 



through the translucent shell. 



c. Section of both valves. 



d. Interior of dorsal valve, with spiral processes restored. (Suess.) 



The following table of genera of marine shells from the Hallstadt 

 and St. Cassian beds, drawn up on the joint authority of MM. Suess 

 and Woodward, shows how many connecting links between the fauna 

 of primary and secondary rocks are supplied by the St. Cassian and 

 Hallstadt beds. 



