PSARONIUS 303 



well-marked formation of secondary wood. A similar 

 peculiarity has since been observed in a specimen of one 

 of the Permian species. These are the only instances 

 in which any trace of secondary tissues has been 

 observed in the Psaronii, apart from the quite peculiar 

 case of the radiciferous cortex. 



The petioles of these Ferns have occasionally been 

 found apart from the stems, and bear the generic name 

 of Stipitopteris. They are identified by the comparison 

 between their transverse section and the marks on the 

 leaf-scars of the Psaronii in the Caulopteris condition. 

 It appears that the petiole usually received a single 

 large bundle with a horse-shoe section, the opening 

 being on the upper side, with the free ends either 

 strongly incurved, or replaced by a distinct strand, 

 lying within the curve of the main bundle. 



M. Grand'Eury, in his researches on the Coal-flora of 

 the Loire, 1 found the stems of Psaronius, in situ, stand- 

 ing erect and rooted as they had grown. From the 

 evidence of constant association, he has no doubt that 

 their fronds were of the Pecopteris type, and identical 

 with those on which fructifications such as Asterotheca 

 and Scolecopteris were borne. This conclusion, which 

 is confirmed by M. Renault's studies on the anatomy of 

 certain Pecopteris leaves, would tend to show that the 

 Psaronii were the stems of arborescent Marattiaceae, 

 and there is little doubt that this was their true nature. 

 There are, of course, various differences in detail, as, 

 for example, in the great development of the sclerenchy- 

 matous tissues and in the single leaf-trace, points in 

 which Psaronius diverges from the recent family. 



1 Flore carbonifire du Dipartevient de la Loire, 1878, pp. 78-98. 



