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THE AMERICAN NATURALIST [Vol. XL VI 



Marattia-like synangia. So clear is the evidence that 

 Scott has called these arborescent Marattias, of the later ^ 

 Paleozoic, Paheo-Marattiaceae, and they may well stand 

 for the precursors of the much humbler Marattias of 

 to-day. 



But these ancient Marattia-\ike forms were not the 

 oldest ferns, for paleobotany has revealed a much older 

 assemblage of undoubted ferns, so old, in fact, that the 

 assemblage is called Primofilices. They are represented 

 not only by numerous detached sporangia, many of which 

 have the annulus characteristic of modern leptosporan- 

 giates, but all the essential structures of one well-char- 

 acterized family, the Botryopterideae, are known. These 

 still somewhat vague Primofilices are extremely suggest- 

 ive and perplexing. The free sporangia and the annulus 

 of the BotryopteridesB suggest leptosporangiate connec- 

 tions ; but the sporangia are not borne as among the lep- 

 tosporangiates, nor is the annulus of the same character. 

 The sporangia are in clusters terminating the bare 

 branches of a rachis ; and the annulus is a vertical, multi- 

 seriate band on one side or both sides of the sporangium. 

 In fact, the so-called "rudimentary" annulus of Osmunda 

 suggests a reduced multiseriate annulus of one of the 

 BotryopteridesB. The vascular system, however, is very 

 characteristic and very primitive, and is so varied as to 

 suggest a synthetic type that might have given rise to all 

 the diversities found in modern ferns. 



The possibilities of paleobotany are well shown in con- 

 nection with these Primofilices. One of its form-genera, 

 Stauropteris, known only as sporangia, has been discov- 

 ered by Scott with germinating spores. The germination 

 of a fern spore is so different from that of a microspore 

 of gymnosperms, or of any other heterosporous plant 

 with which we are acquainted, that it is clear that Staur- 

 opteris is a fern sporangium and not the microsporan- 

 gium of some gymnosperm. When germinating spores 

 are preserved, and also the swimming sperms of paleo- 

 zoic gymnosperms, as recently described, we may expect 



