Rev. A. Irving — On the Permian and Trias. 277 



Ferns, and Calamites, and therefore in by far the greatest proportion 

 of land-plants. Among these, and ranging backwards through 

 Carboniferous to the Middle Devonian, the well-developed genera 

 Calamites (with the highl}'- characteristic G. gigas, Brong.), 

 Annularia, Aster opliyllites, Sphenopteris, Odontopteris, are met with 

 in numerous species ; also the genus Cyatheites (G. arbor escens) is 

 widely spread, and the Carboniferous cycad-genus Noeggerathia 

 equally so. On the other hand, Lepidodendron is of much rarer 

 occurrence than in the Carboniferous period ; Sigillaria and Stigmaria 

 have almost completely died out. The stems of the Tree-ferns of 

 this period are preserved in greater perfection and beauty through 

 the silicification of their tissues, and on this account, as well as on 

 account of their general prevalence, they are to be regarded as very 

 characteristic of the Post-Carboniferous period. To these belong 

 Psaronarius and Tubicaidis. Great significance attaches to the genus 

 Walchia, with its closely -packed angular leaves. The remains of the 

 land-flora of the period are in the main confined to the Eothliegende 

 or lower member of the Dyas ; but the marine group of strata above 

 these furnishes commonly Fucoids (e.g. C aider piles) , and along with 

 these drifted ferns, and especially the twigs and fruits (their forms 

 preserved as iron-pyrites) of a conifer (tfllmannia Bronni, Gopp.) 

 allied to Cupressus sempervirens. [According to Sir Charles Lyell,^ 

 about 18 or 20 siDecies are known in the Permian rocks of England, 

 and no less than 60 in those of Saxony.] 



If now we compare the floras of the Dyas and Trias, a decided 

 difference is observable. According to Credner, the Equiseta (E. 

 arenaceum and E. columnar e) , which in the Trias appear for 

 the first time, are widely distributed, not only over Europe, but 

 also over the east of North America. The genera of Triassic 

 ferns are new except PcBcopteris and Tceniopteris. While in the 

 Palasozoic period vascular cryptogams make up almost exclu- 

 sively the flora, they recede far into the background in Triassic 

 times, and more especially in Keuperian times, before the de- 

 velopment of Cycads and Conifers. The flora of the Muschelkalk 

 is limited to a few questionable Algcs, and small drifted frag- 

 ments of ferns. In the earlier Triassic period the older genera of 

 ferns are superseded by Anomopteris, Clathropteris, Gutbieria, Sageno- 

 pteris. Among Cycads appear Pterophylluin, Zamites, Otozamites, 

 and Pterozamites, and among Conifers, Voltzia and Albertia. 



[Sir Charles Lyell remarked in Student's Elements (p. 384) that 

 " upon the whole the plants of the Marl-slate (the base of the Mag- 

 nesian Limestone in the North of England) differ considerably from 

 those of the Coal-period ; the plants of the Rothliegende of Germany 

 show a close generic affinity with Carboniferous forms." A consider- 

 able addition has recently been made to the known flora of the 

 Marl-slate series of this country by tlie labours of Mr. E. Wilson, 

 F.G.S., who has collected a great number of specimens from this 

 formation, owing to its exposure in railway cuttings in Nottingham- 



1 Studini's Elements of Geology, p. 383. 



