Pteridospermeae 211 



association between the seed and the plant 1 . The structure of the 

 seed of Lyginodendron, proved to be of the same general type as 

 that of the Cycads, as shown especially by the presence of a pollen- 

 chamber or special cavity for the reception of the pollen-grains, an 

 organ only known in the Cycads and Ginkgo among recent plants. 



Within a few months after the discovery of the seed of Lygino- 

 dendron, Kidston found the large, nut-like seed of a Neuropteris, 

 another fern-like Carboniferous plant, in actual connection with the 

 pinnules of the frond, and since then seeds have been observed on 

 the frond in species of Aneimites and Pecopteris, and a vast body 

 of evidence, direct or indirect, has accumulated, showing that a large 

 proportion of the Palaeozoic plants formerly classed as Ferns were in 

 reality reproduced by seeds of the same type as those of recent 

 Cycadaceae 2 . At the same time, the anatomical structure, where it 

 is open to investigation, confirms the suggestion given by the habit, 

 and shows that these early seed-bearing plants had a real affinity 

 with Ferns. This conclusion received strong corroboration when 

 Kidston, in 1905, discovered the male organs of Lyginodendron, and 

 showed that they were identical with a fructification of the genus 

 Crossotheca, hitherto regarded as belonging to Marattiaceous Ferns 3 . 



The general conclusion which follows from the various obser- 

 vations alluded to, is that in Palaeozoic times there was a great 

 body of plants (including, as it appears, a large majority of the 

 fossils previously regarded as Ferns) which had attained the rank of 

 Spermophyta, bearing seeds of a Cycadean type on fronds scarcely 

 differing from the vegetative foliage, and in other respects, namely 

 anatomy, habit and the structure of the pollen-bearing organs, re- 

 taining many of the characters of Ferns. From this extensive class 

 of plants, to which the name Pteridospermeae has been given, it 

 can scarcely be doubted that the abundant Cycadophyta, of the 

 succeeding Mesozoic period, were derived. This conclusion is of 

 far-reaching significance, for we have already found reason to think 

 that the Angiosperms themselves sprang, in later times, from the 

 Cycadophytic stock ; it thus appears that the Fern-phylum, taken in 

 a broad sense, ultimately represents the source from which the main 

 line of descent of the Phanerogams took its rise. 



It must further be borne in mind that in the Palaeozoic period 

 there existed another group of seed-bearing plants, the Cordaiteae, 



1 F. W. Oliver and D. H. Scott, "On the Structure of the Palaeozoic Seed, Lagenostoma 

 tomaxi, etc." Phil. Trans. Royal Soc. Vol. 197, b. 1904. 



2 A summary of the evidence will be found in the writer's article "On the present 

 position of Palaeozoic Botany," Progressus Rei Botanicae, 1907, p. 139, and Studies in 

 Fossil Botany, Vol. n. (2nd edit.) London, 1909. 



3 Kidston, " On the Microsporangia of the Pteridospermeae, etc." Phil. Trans. Royal 

 Soc. Vol. 198, b. 1906. 



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