1 66 FILICES. 



literature under various generic names, Chelepteris, Cda, Bathypteris, 

 Eichw., Sphallopteris, Sch., Anomorhoea, Eichw. Figures and explanations 

 of these objects are to be found in abundance in Schimper's Paleontologie 

 Vegetale. Another genus is Rhizomopteris, Schpr, embracing creeping fern- 

 rhizomes, of which however there are not too many known. Nathorst l 

 has figured some fine specimens from the Rhaetic beds of Schonen. One 

 more genus may be mentioned, Schizodendron 2 ,with a few stems of similar 

 appearance which have been described by Zeiller 3 . In other forms some 

 characters at least may be obtained from the mode of arrangement of the 

 bundle-traces on the leaf-scars, and genera may thus be distinguished, 

 though these too have but little real importance, as is shown by the fact 

 that the distribution of the bundles even in recent Ferns becomes so much 

 changed in the base of the leaf and within small distances, that stems with 

 simple scars and stems clothed with leaf-bases cannot be compared together. 

 Moreover Zeiller 4 has recently shown that two of the genera to be men- 

 tioned here, Stemmatopteris, Cda, and Caulopteris, Cda (not Lindl. and 

 Hutt.) may be omitted as being different surface-impressions of the same 

 stem. These two form-genera have on their surface large circular or ellip- 

 tical scars, which in the former are sharply defined and smooth, in the 

 latter forked, and which almost touch one another in the orthostichies. 

 Each scar contains a closed circular or elliptical trace, and inside this 

 another small trace in the form of a V or U opening upwards. Zeiller 5 

 would see in the peripheral contour-line of the scar the boundary line of the 

 leaf-cushion, in the outer trace the boundary-line of the detached leaf-stalk, 

 and only in the inner V the bundle-trace. But it is also possible that, as 

 was supposed by the older authors fi , the inner circular line may represent 

 the trace of a circular vascular bundle, in which case the V would answer 

 to the emerging strand of a medullary bundle-system. We cannot hope to 

 determine this point till we find a stem of the kind with its structure pre- 

 served, and this has not yet been done. The name Protopteris is given by 

 Corda to all stems which have a single trace in their leaf-scars of the shape 

 here represented 3 . He has described several of these stems from the Coal- 

 measures 7 , and one of the same kind from the Permian formation under the 

 name of Thamnopteris Schlechtendalii 8 . Protopteris Witteana 9 belongs 

 to the Wealden, the stem named Dicksonia Buvignieri 10 to the Chalk. 

 Other individuals from the Chalk of Bohemia with a more complex and 

 many-stranded trace in the leaf-scars will be found figured in O. Feistmantel n 

 as Alsophilina Kaunitziana, Dorm., and Oncopteris Nettwallii, Dorm. 



1 Nalhorst (2), t. i, and (4), t. i. " Eichwald (1), vol. i, 19, f. 9, and t. 20, f. 11. * Zeiller 



(9), t. 18. 4 Zeiller (9) and (10). s Zeiller (9). 6 Schimper (1). 7 Corda (1). 



Eichwald (1), vol. i, t. 3, ff. 2, 3. Schenk (1), p. 226. t. 30, f. 6. 10 Renault (2), 

 vol. Hi, p. 73, t. 9. " O. Feistmantel 4), t. 2, ff. 3, 4. 



