172 FIL1CES. 



The mass of roots which surrounds the axis may attain an enormous 

 size and much exceed the diameter of the centre of the stem. In the 

 specimens from St. Etienne preserved as casts it appears as a layer of 

 carbonaceous substance, which increases constantly in size as it approaches 

 the base of the stem ; it can be recognised in this form in the sections of 

 Psaronius carbonifer, Cda, figured by Corda l . Its size in the silicified 

 specimens is in favour of the view that they are entirely the bases of stems. 

 Careful examination shows that this peripheral investment consists of two 

 distinct layers : first, the rind of the stem above described which is tra- 

 versed by the roots ; next, a mass of closely interwoven roots which project 

 free above the surface, where they also show ramifications. These roots are 

 of course distinguished from the basal portions in the rind by the circum- 

 stance, that while sharply defined on the outside they still show a narrow 

 parenchymatous rind lying outside the cylinder of sclerenchyma. Speci- 

 mens showing the entire transverse section with the centre of the stem and 

 the whole of the enveloping mass of roots are rare. By far the larger part 

 of the Psaroniae preserved in collections are fragments of the envelopes, 

 sometimes of extraordinary dimensions. Similar silicified masses of en- 

 tangled roots, belonging to other ferns and found in a fragmentary state 

 at Chemnitz, have been described as roots of Protopteris by Stenzel 2 , who 

 compares them with Corda's :i figure of his Protopteris microrhiza. They 

 are distinguished from those of Psaroniae by diarc root-strands. Such 

 strands are found also in the compact root-investment of the stem known 

 as Rhizopterodendron Oppoliense, Gopp. with the structure of Protopteris, 

 which comes from the Turonian beds of Oppeln, and for which Stenzel's 4 

 elaborate description should be consulted. 



Two small fern-stems, in which the thin herbaceous axis is surrounded 

 by a closed woody panoply of leaf-stalk-bases lying close one on another, are 

 described in the literature under the name Osmundites. These are Osmun- 

 dites Schemnicensis 5 from the Tertiary quartz rocks of Ilia in Hungary, and 

 O. Dowkeri c , also a Tertiary fossil from the Lower Eocene beds of Herne 

 Bay in England. A third quite similar silicified specimen, not yet described, 

 was picked up as a loose stone in the alluvium of the lower course of the 

 Lena in Siberia, and has found its way as part of Blumenbach's bequest into 

 the palaeontological collection of the University of Gottingen. The centre 

 of all these stems is occupied by the ring of vascular bundles composed of 

 very irregularly shaped transverse sections of bundles and surrounding the 

 parenchymatous medullary tissue. On the outer side of this ring is a thick 

 envelope of sclerenchyma, which is traversed by the crescent-shaped leaf- 

 bundles, and to which the free leaf-stalks ultimately become attached. The 



1 Corda (1), t. zS. 2 Stenzel (2,. 3 Corda ;i /? t. 50, ff. 7-10. ' Stenzel (3 . 



s linger ffc). ' Carruthers (8" . 



