376 ELEMENTS OE GEOLOGY. 
placoid fish and of Rays, and of the genera Saurichthys and 
Fig.39T. Gyrolepis (Figs. 387, 388, p. 367). 
The plants of the Ken per are ge- 
nerically very analogous to those 
of the oolite and lias, consisting of 
ferns, equisetaceous plants, cycads, 
and conifers, with a few doubtful 
monocotyledons. A few species 
such as Equisetites columnaris^ are 
common to this group and the 
(Syn.^^m- oolite. 
St, Cassian and Hallstadt Beds 
(see Map, Fig. 398).—The sand¬ 
stones and clay of the Keuper resemble the deposits of es¬ 
tuaries and a shallow sea near the land, and afford, in the 
N.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 op¬ 
portunity of bringing their remains to light. This, it is be¬ 
lieved, has at length been accomplished, by the position now 
assigned to certain Alpine rocks called the ‘‘St. Cassian beds,” 
Equisetites columnaris. 
setum columnare.) Fragment of 
stem, and a small portion of same 
magnified. Keuper. 
Fig. 398. 
the true place of which in the series was until lately a sub¬ 
ject of much doubt and discussion. 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, M. Suess of 
Vienna and others, have satisfied themselves that the Hall¬ 
stadt formation is referable to the period of the Upper Trias. 
