146 



ANCIENT PLANTS 



teristics of the plants, while in their internal anatomy 

 the hollow stems have very little w r ood, which is arranged 

 in a series of small bundles, each associated with a hollow 

 canal in the ground tissue. 



The family stands apart from all others, and even 

 between it and the group of Lycopods there seems to 

 be a big gap across which stretch no bonds of affinity. 

 Has the group always been in a similar position, and 

 stood isolated in a backwater of the stream of plant 



life? 



In the late Tertiary 

 period they seem to have 

 held much the same posi- 

 tion as they do now, and 

 we learn nothing new of 

 them from rocks of that 

 age. When, however, we 

 come to the Mesozoic, the 

 members of the family are 

 of greater size, though they 

 appear (to judge from their 

 external appearance) to 

 have been practically iden- 

 tical with those now living in all their arrangements. 

 In some beds their impressions are very numerous, but 

 unfortunately most are without any indication of internal 

 structure. Fossils from the Mesozoic are called Equise- 

 tites, a name which indicates that they come very close 

 to the living ones in their characters. In the Lower 

 Mesozoic some of these stems seem to have reached the 

 great size of a couple of feet in circumference, but to 

 have no essential difference from the others of the 

 group. 



When, however, we come to the Palaeozoic rocks we 

 find many specimens with their structure preserved, and 

 we are at once in a very different position as regards 

 the family. 



First in the Permian we meet with the important 



Fig. 103. Impression of Leaf Whorl 

 of Equisetites from the Mesozoic Rocks, 

 showing the narrow toothed form of the 

 leaves. (Photo.) 



