CYCADOFILICALES 53 



(60), an ancestral race which combined the characters of the modern 

 groups. Tn fact, the existence of leptosporangiate ferns, in the mod- 

 ern sense, has not been recognized until the Permian, and during 

 the Mesozoic the group was a dominant one and its modern families 

 became differentiated ; while evidence of the existence of eus[)orangiate 

 ferns, in the modern sense, is not satisfactory until the Tertiary 

 (60, 61). 



Paleozoic Marattiaceae (82). — The very large {proportion of 

 synangia belonging to the carboniferous flora led to the inference 

 that the Marattiaceae were conspicuously represented. All types 

 of sporangia, from free to united (synangia), occur on leaves referred 

 to Pecopteris, and one Pecopteris (P. Pluckenetii) has been found to 

 be seed-bearing. It was natural to raise the question whether all 

 of the sporangia referred to Marattiaceae are not microsporangia. 

 But Pecopteris is a very large frond genus, and such sporangium 

 genera as Ptychocarpus, Asierotheca, Scolecopteris, and Daneites, 

 which are synangia borne on the ordinary foliage, have every right 

 to be regarded as belonging to the Marattiaceae until there is absolute 

 proof to the contrary. Such forms are characteristic of the Permian 

 and Upper Coal-measures, and are not known to occur in the Lower 

 Carboniferous. 



In addition to this evidence of the existence of paleozoic Marat- 

 tiaceae, which may be regarded as negative, there is positive evidence 

 from the anatomy of Psaronius, a stem genus occurring at the same 

 horizons. The fronds borne by this stem were of the Pecopteris 

 type (42), as shown by constant association, and are identical u'ith 

 those bearing such sporangia as Asierotheca and Scolecopteris. 

 Repeated investigation of the anatomy of these stems and leaves 

 has strongly confirmed the belief that the species of Psaronius were 

 stems of arborescent members of the Marattiaceae. Some of these 

 permo-carboniferous trees were of great size, reaching a height of 

 18 to 20 m. The stems were complex polystelic and the roots poly- 

 arch, the whole structure more nearly resembling the vascular struc- 

 ture of the Marattiaceae than of any other known stems. A species 

 (P. Renaultii) from the Lower Coal-measures is of exceptional 

 antiquity and simplicity, being monostelic, a single endarch vascular 

 cylinder inclosing pith. 



