94 



THE CHAIN OF LIFE. 



Thus land vegetation begins with the highest members of 

 the lower of the two great series into which botanists divide 

 the vegetable kingdom. 



If we now turn to the Upper Silurian, further evidence ot 

 land vegetation presents itself. Near the base of this great 

 series, the club-moss family is represented by a plant discovered 

 by Claypole in the Clinton group, and referred to a new genus 

 {Glyptodendron, Fig. 86). Plants of this family have also 

 been noticed by Barrande in Bohemia, and by Page in Scotland. 

 Their spore-cases have been recognised by Hooker in the 

 Ludlow of England ; and a humble but interesting member of 

 this family, connecting it with the pillworts, Psilophytoti 



Fig. 86. —Fragment of outer surface oiGlyptodendron of Claypole. An Upper 



Silurian '1 ree. 



(Fig. 87), though more characteristic of the Devonian, has 

 been found in the Upper Silurian both in Canada and 

 the United States, No Ferns or Equiseta have as yet been 

 found in the Upper Silurian ; but in 1870 I recognised in some 

 fragments of wood from the Ludlow bone-bed, in the Museum 

 of the Geological Survey of Great Britain, the structure of that 

 curious prototype of the Pine tribe, to which I have given the 

 name Frotofaxites, and which was first recognised in the 

 Devonian of Gaspd 



It is probable that these discoveries represent merely a small 

 proportion of the plants actually existing in the Upper 

 Silurian period. All the deposits of this age at present known 



