Johnson — is Archceopteris a Pteridosperm? 133 



5. The diclioloniy of tlie veins and the absence of a midrib in tlie pinnules 

 are wortliy of note as indicative of a primitive type. 



Tlie external characters of the vegetative organs, as far as known are, it 

 tlius seems, of no taxonomic value in decidiug as to tlie positiou of 

 Archseopteris. Until the discovery of the Pteridosperms such characters were 

 regarded as Filicinean. 



6. The fertile frond of ArcliEeopteris, with its partial separation into 

 vegetative and reproductive regions, is comparable to the fertile frond of the 

 Osinundacese, Ophioglossacese, and of Aneimia in the Schizseacese. 



ISTothing like Archteopteris is known iu the Pteridosperuis at present. 

 It would be dangerous to use this, possibly imperfect and "impressionist" 

 knowledge, as an argument against the iuclusiou of Archseopteris in the 

 Pteridosperms. 



7. The lobed sporophyllule of Archseopteris is more suggestive of 

 affinities with Spheiiophyllum and OiJhioglossum than with a Pteriiiosperm . 



The sporangium of the great majority of the living Pteridophyta is 

 avascular. 



In the extant Ophioglossacese and the extinct Botryopteridese, as repre- 

 sented by Zygopteris, the sporangium is vascular, i.e., vascular tissue runs 

 through the stalk of the sporangium, and either ends below it, or as in 

 Ophioglossum, runs on and sends off veins between the sporangia. 



In the vascularity -of tlio sporangium Archse )pteris is comparable among 

 ferns with the Ophioglossacese. The miorosporaugia of a Pteridosperm (e.g. 

 the bilocular sporangia of Crossotheoa) are also in a sense vascular, i.e. the 

 sporophyll segment bearing the sporangia is vascular. 



8. The sporangium of Archseopteris is apparently divided by transverse 

 septa into a series of superposed loculi comparable to one half of a small 

 " sporangiferous spike " of an Ophioglossum. Xo Pteridosperm microsporan- 

 gium, so divided horizoutally, is kuown ; but iu living Angiosperms there 

 are many genera which possess microsporangia or pollen-sacs made 

 multilocular by horizontal partitions. 



9. Archseopteris is now known from widely-separated localities in different 

 parts of the world — Ireland, Scotland, Belgium, Germany, Russia, China (?), 

 Bear Island, Ellesmere Land, Eastern Canada, and Eastern United States. 



In no locality have seed-like bodies been found, connected directly or 

 indirectly with the plant. On the other hand, the localities have, as a rule, 

 not been exhaustively examined for Archseopteris, and no locality has been 

 investigated since the Pteridosperms, as a seed-bearing group, were 

 founded. 



