468 STUDIES IN FOSSIL BOTANY 



showing seeds. We may hope for more detailed 

 information on this interesting point. 1 



There is another species of Pecopteris, P. Sterzeli, 

 Zeiller, which so closely resembles P. Pluckeneti, in the 

 form and mode of branching of the frond, that Professor 

 Zeiller has no doubt that this too was a Pteridosperm, 

 though the seeds have not yet been observed. There 

 is evidence of considerable weight that the fronds of 

 P. Sterzeli were borne on a Caulopteris stem — Caulopteris, 

 as already stated, representing the casts of " Tree-fern " 

 stems, the structure which, when known, is that of 

 Psaronius (Vol. I. p. 295). Although Professor Zeiller 

 no longer regards the connection between Pecopteris 

 Sterzeli and the Caulopteris as proved, it seems desirable 

 to call attention to the question, for there appears to 

 be little reason for doubting the evidence, beyond the a 

 priori improbability of a seed-bearing plant having had 

 the stem of a supposed Marattiaceous Tree-fern. 2 If 

 Professor Zeiller's original opinion should be confirmed 

 by future investigation, the relation of the Marattiaceous 

 to the Pteridospermous Pecopterids will need serious 

 reconsideration. 



It has already been mentioned (Vol. I. p. 289) 

 that additional evidence for the Pteridospermous nature 

 of certain Pecopterids is afforded by the fact that 

 they bore fructifications of the Crossotheca type. Mr. 

 Kidston 8 enumerates three species of Crossotheca in 

 which the foliage is known to have been that of a 



1 See Grand'Eury, " Surles Inflorescences des Fougeres a Graines " etc. 

 Comptes Rendtts, t. cxliii. p. 764, 1906. 



2 For the history of this question see Zeiller, Flore Fossile de Commentry, 

 Pt. i. t. 1888, p. 184, Plate viii. ; Bassin Houiller et Permien de Blanzy 

 Flore Fossile, 1906, p. 62. 



3 Microsfiorangia of the Ptcridospermeae, p. 432. 



