The Present Position of Palaeozoic Botany. 201 



to its lower surface. In all respects the fructification agrees with 

 Crossotheca (see Fig. 17, F) and it is named Crossotheca Höningliausi 

 by Mr. Kids ton. Though the specimens are not in the petrified 

 condition it was found possible to isolate the microspores, which are 

 still contained in the sporangia. 



It is a point of great interest that the male fructification of 

 Lyginodendmn should have been borne on the same frond which else- 

 where shows the usual vegetative characters. In this respect Lygino- 

 dendron was at a lower stage of differentiation than many Ferns, and 

 far below the level of any Seed-plants previously known. 



About a year before Mr. Kids ton' s discovery. Miss M. Benson 

 had described a synangic fructification, with structure preserved, which 

 she named Telangium Scotti, and was inclined to refer to Lijginodendron.^) 

 In this fructification from 4 to 8 long, pointed sporangia are parti- 

 ally united to form synangia, much like some of those attributed to 

 Marattiaceae. The best evidence for reference to Lyginodendron was 

 afforded by the spores, which agree very nearly with the pollen-grains 

 found within the pollen-chamber of species of Lagenosfoma. From ob- 

 servations of my own I think" it probable that Miss Benson's Telangium 

 may turn out to have been a Crossotheca and that the bilocular spor- 

 angia observed by Mr. Kids ton may be an indication of synangic 

 structure. 



In any case it appears that the reproductive organs of Lygino- 

 dendron present the same combination of cliaracters which is shown 

 so clearly in the vegetative structure. While the highlj^ organized 

 seed strongly indicates Cycadean affinities, the microsporangiate fructi- 

 fication is entirely Fern-like in its nature. 



I have described Lyginodendron oldhammm at some length, be- 

 cause, from our exceptionall}^ complete knowledge of the plant in all 

 its parts, it may best serve as the type of the Pteridospermeae. We 

 will now pass rapidly in review the evidence regarding other members 

 of the class. 



Before leaving the Lyginodendreae, it may be pointed out that 

 Heterangium (with the foliage of Splienopteris elegans and other species) 

 though its fructification is not yet known, is clearly shown by its 

 anatomical structure to belong to the same family with Lyginodendron. 

 Anatomicall}^ it stands at a lower level than that genus, for its 

 vascular cylinder is without a pith, constituting a protostele ana- 

 logous to that occurring in most species of the recent Fern-genus 

 Gleklienia. 



1) Ann. of Bot., Vol. 18, 1904. 



