426 Structural and Physiological , Botany. 
contain any quantity of plants, and then chiefly in a silicified. 
state. The MJagnesian Limestone which rests upon it con- 
tains but very few vegetable remains. The Permian has 
only one form in common with the lower, and only a few 
with the upper strata of the Carboniferous system. The 
prevalent forms are still Sigillariz, Calamites, Ferns, Lepi- 
dodendra, &c.; but in addition are found Palms and — 
Cycadez, the latter order attaining here their maximum 
development. | 
A different vegetation characterises the Secondary or 
Mesozoic strata. The forms characteristic of the Paleozoic 
beds, Sigillariz, Lepidodendra, and Asterophyllites, disap- 
pear, and others make their appearance which bear a greater 
resemblance to those of the present day. The Conifere 
began in the Devonian, attained a maximum in the Carboni- 
ferous, and again diminished in the Permian system. 
In the lowest system belonging to the Secondary strata, 
the Z7zas, Coniferee must have formed the main part of the 
_ forests ; while of Cryptoganis, so largely developed in the 
lower rocks, only Ferns remain, those howéver belonging to 
new, and partly to pecuhar and highly developed genera. 
The chief forms of Coniferze in these forests were species of 
Voltzia (Fig. 543) and Albertia. The former were lofty 
trees, not unlike our Cryptomeria, while the latter had broad 
leaves penetrated by delicate longitudinal veins. With 
them are associated certain Cycadeze (Zamites, Figs. 545, 
546) and water-plants, as well as Calamites with verticillate 
leaves, and gigantic Equisetaceee, which may have clothed the 
margins of the sheets of water. Of the three well-characterised) 
sections into which the Trias is divided, the lowest or 
Bunter Sandstein contains but few vegetable remains, the 
middle or Wuschelkalk scarcely any, and the uppermost or 
Keuper only a few. The flora of the Trias, in its gigantic 
Ferns and peculiar Coniferee, bears a greater resemblance to 
that of New Zealand than of any other country at the present 
time. 3 tL 
