THE FERNS 535 
We know that during the coal age many tree-ferns like the 
Pecopteris shown in Fig. 277 (page 299), apparently near of 
kin to the adder-tongues, produced stout trunks bearing a 
crown of ample leaves nearly twenty meters above the 
ground. 
Fic. 360.—Tree-Ferns and Herbaceous Ferns. (Baillon.) 
At the present day tree-ferns such as the one shown in 
Fig. 360 abound in moist, warm regions, although the ferns 
most common in northern lands are more like the smaller 
ones shown in the same illustration. Thus it would appear 
that a certain amount of degeneration has attended the 
adaptation of ferns to the more stringent conditions of cold 
