THE ERIAN OR DEVONIAN FORESTS. 77 



stem from the Erian of New York, there is also a special 

 arrangement for support, consisting of a series of pecul- 

 iarly arranged radiating plates of scalariform vessels, not 

 exactly like those of an exogenous stem, but doing duty 

 for it (Asteropteris)* 

 Similar plants have 

 been described from 

 the Erian of Falken- 

 berg, in Germany, 

 and of Saalfeld, in 

 Thuringia, by Goep- 

 pert and Unger, and 

 are referred to ferns 

 by the former, but 

 treated as doubtful 

 by the latter, f This 

 peculiar type of tree- 

 fern is apparently a 

 precursor of the more 

 exogenous type of 

 Heterangiam, recent- 

 ly described and re- 

 ferred to ferns by 

 Williamson. Here, 

 again, we have a me- 

 chanical contrivance 

 now restricted to 

 higher plants appro- 

 priated by these old 

 cryptogams. 



The history of the ferns in geological time is remark- 

 ably different from that of the Lycopods ; for while the 



* "Journal of the Geological Society," London, 1881. 



f " Sphenopteris Refracta," Goeppert; "Flora des Uebergangsge- 

 birges." " Cladoxylon Mirabile," Unger ; " Palaeontologie des Thuringer 

 Waldes." 



Fig. 27. — Calamites radiatus (Erian, New 

 Brunswick). 



