434 ST. CASSIAN AND HALLSTADT BEDS. [Ch. XXII. 



Nothosaurus mirabilis. The saurian called Belodon by H. Von 

 Meyer, of the Thecodont family, is another Triassic form, associated 

 at Diegerloch with Microlestes. 



Beneath this bone-breccia follows the regular series of strata called 

 Keuper, which in Wurtemberg is about 1000 feet thick. It is divided 

 by Alberti into sandstone, gypsum, and carbonaceous slate clay.* 

 Remains of reptiles called Nothosaurus and Phytosaurus have been 



found in it with Ldbyrinthodon ; the 

 Ei £- 466 - detached teeth, also, of placoid fish and 



of rays, and of the genera Saurichthys 

 and Gyrolepis (figs. 481, 482, p. 442). 



The plants of the Keuper are generic- 

 ally very analogous to those of the lias 

 and oolite, consisting of ferns, equiseta- 

 ceous plants, cycads, and conifers, with 

 a few doubtful monocotyledons. A few 

 Equiseutes coiwmnaris. (Syn. Equi- species such as Equisetites columnaris, 





columnare) Fragment of are common to this PTOUD and the 

 stem, and a small portion of same a ± 



magnified. Keuper. OOllte. 



St. Cassian and Hallstadt Beds. — The 

 sandstones and clay of the Keuper resemble the deposits of estu- 

 aries and a shallow sea near the land, and afford, in the K "W. of 

 Germany, as in France and England, but a scanty representation of 

 the marine life of that period. We might, however, have anticipated, 

 from its rich reptilian fauna, that the contemporaneous inhabitants of 

 the sea of the Keuper period would be very numerous, should we 

 ever have an opportunity of bringing their remains to light. This, it 

 is believed, has at length been accomplished, by the position now 

 assigned to certain Alpine rocks called the " St. Cassian beds," the 

 true place of which in the series was until lately a subject of much 

 doubt and discussion. For valuable researches relating to these for- 

 mations, we are indebted to many eminent geologists, especially to 

 MM. Yon Buch, E. de Beaumont, Murchison, Sedgwick, and Klip- 

 stein, and in Switzerland to MM. Escher and Merian, and more lately 

 in Austria to MM. Yon Hauer, Suess, Homes, and Giimbel. It has 

 been proved that the Hallstadt beds on the Northern flanks of the 

 Austrian Alps correspond in age with the St. Cassian beds on their 

 southern declivity, and the Austrian geologists hence satisfied them- 

 selves that the Hallstadt formation is referable to the period of the 

 Upper Trias. Assuming this conclusion to be correct, we become 

 acquainted suddenly and unexpectedly with a rich marine fauna be- 

 longing to a period previously believed to be very barren of organic 

 remains, because in England, France, and Northern Germany the 

 Upper Trias is chiefly represented by beds of fresh or brackish-water 

 origin. Mr. Edward Suess, of Vienna, to whom we are indebted for 



* Monog. des Bunten Sandsteins. 



