72 



THE GEOLOGICAL HISTORY OF PLANTS. 



Fig. 22. — Erian ferns (New 

 Brunswick), a, Aneimites 

 obtusa. c, JSfeuropteris poly- 

 morpha. r, Sphenopte: 

 pilosa. n, Hymenop^ 

 subfurcatus. 



Another group of plants which 

 attained to great development in 

 the Erian age is that of the Ferns 

 or Brackens. The oldest of these 

 yet known are found in the Mid- 

 dle Erian. The Eopteris of Sa- 

 porta, from the Silurian, at one 

 time supposed to carry this type 

 much further back, has unfortu- 

 nately been found to be a mere 

 imitative form, consisting of 

 films of pyrites of leaf -like shapes, 

 and produced by crystallisation. 

 In the Middle Erian, however, 

 more especially in North Ameri- 

 ca, many species have been found 

 (Figs. 22 to 24).* I have myself 

 recorded more than thirty spe- 

 cies from the Middle Erian of 

 Canada, and these belong to sev- 

 eral of the genera found in the 

 Carboniferous, though some are 

 peculiar to the Erian. Of the 

 latter, the best known are per- 

 haps those of the genus ArchcB- 

 opteris (Fig. 24), so abundant 

 in the plant-beds of Kiltorcan 

 in Ireland, as well as in North 

 America. In this genus the 

 fronds are large and luxuriant, 

 with broad obovate pinnules de- 

 current, on the leaf-stalk, and 

 with simple sac-like spore-cases 

 borne on modified pinnae. An- 

 other very beautiful fern found 



' For descriptions of these ferns, see reports cited above. 



