82 STUDIES IN FOSSIL BOTANY 



Vascular Cryptogams, closely allied to the recent 

 Horsetails. But, although none but Cryptogamic 

 Calamarieae are known to us, the question remains 

 whether they show marked affinities to any of the 

 groups of Seed-bearing Plants, or are likely to have lain 

 on or near any of the lines of Phanerogamic descent. 



If there were any such affinity, it would appear to 

 lie in the direction of Coniferae, or possibly, as 

 M. Renault suggested, of Gnetaceae. The anatomy 

 of the stem certainly approaches that of the former 

 family, while the usually simple form and structure of 

 the leaves may be regarded as pointing the same way. 

 Even the fructifications are not without analogy in the 

 two groups. The relative position of the sporangio- 

 phore and bract in Palaeostachya has been compared 

 with that of the ovuliferous and carpellary scale in 

 Abietineae. I was at one time disposed to attach 

 some weight to these various considerations, as indi- 

 cative of affinity. It is more probable, however, that 

 these points of resemblance between Calamarians and 

 Conifers are nothing more than analogies — interesting 

 examples of parallel development, but not marks of 

 relationship. There is an entire absence of transitional 

 forms between Equisetineae and either Coniferae or 

 Gnetaceae, whereas, as we shall see later on, there 

 is strong evidence for the derivation of the 

 Gymnosperms generally (or at least of the Cycads 

 and Conifers) from a different Cryptogamic stock, 

 namely that of the Ferns. 



8. Mesozoic Equisetales. — The Calamarieae hitherto 

 considered are strictly Palaeozoic plants ; the last 



