66 



THE GEOLOGICAL HISTORY OF PLANTS. 



taken for scales. No spores could be observed in any of 

 the specimens, though in some the surface was marked 

 by slight, rounded prominences, possibly the impressions 

 of the spores within. This peculiar and very simple style 



Fig. 21. — Zepidodendron and Psilophyton (Erian, New Brunswick). 



a, Zepidodendron Gaspianum. b, c, Psilophyton elegans. 



of spore-case is also characteristic of other species, and 

 gives to Psilophyton a very distinct generic character. 

 These naked spore-cases may be compared to those of 

 such lycopodiaceous plants as Psilotum, in which the 



