LATEE LIFE ON THE EAETH 45 



Lycopodiacece. In fossil ferns the fructification is 

 rarely preserved, so that the arrangement of the 

 venation of the fronds has to be largely used in their 

 discrimination ; and this makes their classification 

 doubtful. Most of the Carboniferous ferns look 

 much like modern ones, and some certainly belong 

 to living families ; but Megaphyton was a remarkable 

 tree-fern with only two rows of large fronds , one on 

 each side of the stem. Sigillaria connects the vas- 

 cular Cryptogams with the Gymnosperms ; for it 

 has the fruit and leaves of a Lycopod, while the 

 internal structure of the stem closely resembles that 

 of the Coniferse ; and Lyginodendron connects the 

 ferns with the Cycads. 10 



The forests were formed by tall spore-bearing 

 trees, chiefly Sigillaria, with its unbranched stems 

 clothed with long grass-like leaves; Lepidodendron, 

 with rough branched stems ; and many tree-ferns. 

 In the swamps were numerous dense clumps of 

 Calamites and Annularia, with hollow, reed-like 

 stems, sometimes a hundred feet in height, and 

 distant whorls of needle-shaped leaves. On the 

 uplands Gymnosperms grew abundantly. Dadoxylon 

 was perhaps related to the fan-leaved Gingko-pine 

 (Salisburia) of China, but it had a large pith ; while 

 Cordaites appears to have been a Cycad, with rela- 

 tions to the broad-leaved yews on one hand, and to 

 Sigillaria on the other. Cordaites and the large 

 Lycopods attained their maximum in the Carboni- 

 ferous period. 



10 Philosophical Transactions, Series B., vol. clxxxvi., 

 p. 765. 



