﻿20 SCOTT, Early History of Seed-bearing Plants. 



distribution of the vascular supply. In other respect? 

 there is a general resemblance in the seeds of the two 

 groups ; in the Cordaiteae, as in the Pteridospermeae,. 

 although the archegonia have been clearly seen, no sign 

 of an embryo has been detected. 



The Cordaiteae evidently bore no resemblance in habit 

 either to ferns or Pteridosperms, nor do we find in their 

 structure any of those fern-like characters which are so 

 marked in the latter class. Their inflorescences also are 

 of a much more advanced nature than the fertile fronds of 

 the fern-like seed-plants, or even than the floral organs of 

 the Cycadaceae. In the Cordaiteae we have evidently to 

 do with a well-characterised Gymnospermous family, far 

 more remote from any Cryptogamic progenitors than the 

 plants previously considered, though their geological 

 record goes equally far back. 



The Cordaiteae, as we have seen, show plain indica- 

 tions of Cycadean affinity, especially in their foliar 

 structure, and in the characters of the seed. Perhaps 

 their nearest ally in the recent flora is the Maidenhair 

 Tree {Ginkgo biloba), which agrees with the Cycads in its 

 fertilization by spermatozoids and generally in the char- 

 acters of the ovule and seed. At the same time it is 

 impossible to ignore points of resemblance between 

 the Cordaiteae and the Coniferae, in habit, anatomical 

 structure, and to some extent in the floral organs. 



Have we then any grounds for connecting this 

 remarkable group with the same stock as the Pterido- 

 spermeae, or must we suppose that it had a totally 

 distinct origin, traceable, perhaps, to some different 

 Cryptogamic phylum ? 



It has already been pointed out that the Cordaitean 

 seed, though different in details from the Pteridospermous- 

 type, yet was not fundamentally distinct. 



