Permian Period. 73 



each other, is the relation which both of them bear to the coal- 

 formations, of which they seem to be a kind of extract, 

 reminding us more especially of the most recent beds. 



" With regard to the plants of the bituminous slates of the 

 Mansfeld district, they are so few in number, and appear to 

 have been deposited in conditions so different, that we can 

 with difficulty compare them with the two other Floras. Yet 

 the species of Sphenopteris are extremely like each other in 

 the three formations, and an exact comparison would per- 

 haps establish the identity of many of them. The Pecopteris 

 crenulata of Ilmenau, is only perhaps an imperfect state of 

 the Pecopteris abbreviata of Lodeve ; lastly, the Callipteris 

 of the Permian formation of Lodeve have a very close con- 

 nection between themselves and the Callipteris of the coal- 

 formation. 



" We may add, with regard to the bituminous slates of 

 Thuringia, that many of these fossils appear to be marine 

 plants, whose numbers would become much more consider- 

 able if we did not suppress all the imperfect impressions which 

 have been described as such, and which are nothing more 

 than fragments of ferns or altered coniferae. 



*' II. Reign of the Gymnosperms. — During the preceding 

 periods, and particularly during the Carboniferous period, the 

 Acrogenous cryptogams predominated, and the Gymnosperm- 

 ous dicotyledons, less numerous, shewed themselves in un- 

 usual forms, and sometimes so anomalous that we are in 

 doubt whether to place them in this or the preceding depart- 

 ment ; such are the Asterophylliteaj. At a later period, on 

 the contrary, these anomalous and ambiguous forms, whose 

 classification is often obscure, disappear ; Acrogenous crypto- 

 gams and Gymnospermous dicotyledons evidently enter into 

 families still existing, differing from them only in generic 

 forms ; the Ferns and Equisetaceae, which represent the acro- 

 gens, are less numerous ; the Coniferse and Cycadeee almost 

 equal them in number, and usually exceed them in frequency, 

 especially in the second period ; by their abundance and size 

 they afford the essential character of all these formations ; 

 lastly, the Angiospermous dicotyledons are wholly wanting, 

 and the monocotyledons fire in very small numbers. 



