662 



ST. CASSIAN BEDS. 



or in the Werfen ; while, on the other hand, the true Muschelkalk is 

 known to exist in the Italian Alps and in Hungary, so that all doubts 

 on this question must very soon be removed. 



Among the 800 species of fossils of the Hallstatt and St. Cassian beds, 

 many are still undescribed ; some are of new and peculiar genera, as 

 Scoliostoma, fig. 4, and Platystoma, fig. 5, among the Gasteropoda ; 

 and Koninckia, fig. 6, among the Brachiopoda. 



Fig. 4 



Fiff. 5. 



Platystoma Suessii, 



Hoernes. 



From Hallstatt. 



Scoliostoma, S. Cassian. 

 Fig. 6. 



Koninckia Leonhardi, Wisswann. 



a. Dorsal view, natural size. 



o. 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 Hallstatt 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 now supplied by the Upper Trias. 



Genera of Fossil Mollusca in the St. Cassian and Hallstatt Beds. 



Common to Older Bocks. 



Cyrtoceras. 



Orthoceras. 



Goniatites. 



°Loxonema. 



°Holopella. 



Murchisonia. 



Euoniphalus. 



Porcellia. 



c Megalodon. 



Cvrtia. 



Characteristic Triassic Genera. 

 Ceratites. 

 Scoliostoma (or Coch- 



learia). 

 Naticella. 

 Platystoma. 

 Isoarea. 

 Pleurophorus. 

 Myophoria. 

 Monotis. 

 Koninckia. 



Common to Newer Bocks. 



Ammonites. 



°Belemnites. 



°Nerinaea. 



Opis. 



Cardita. 



Trigonia. 



Myoconchus. 



Ostrea. 1 sp. 



Plicatula. 



Thecidium. 



The genera marked by an asterisk are given on the authority of Mr. Suess, the 

 rest on that of Mr. Woodward from fossils of the St. Cassian rocks in the British 

 Museum. 



