XVll APPENDIX. 



The specimens apparently belonging to this species before me, 

 present considerable variations of form and other characters, some 

 being decidedly narrower, with their pinuas shorter, more distant, 

 and more oblique, and their pinnules less divided. These, how- 

 ever, probably belong to dift'erent parts of the frond from that 

 described here as the typical form of the species. Others have 

 the pinnaa and pinnules, as well as the subdivisions of the latter, 

 smaller and proportionally more slender, and presenting a more 

 delicate appearance throughout. These latter may possibly be- 

 long to a distinct species, but they agree so nearly in all other 

 respects with the form described as to leave the impression that 

 the whole series belongs to one somewhat variable species. 



This species has much the aspect of a Sphenopteris, to which 

 Dr. Newberry thought it might be referred without impropriety. 

 In this opinion Prof Dawson was inclined to concur on examin- 

 ing a photograph of it. On a critical examination of its nerva- 

 tion, as seen in some specimens sent to him, he writes that he 

 thinks it belongs more properly to the same group as Archseop- 

 teris Halliana (= Sphenopteris laxa, Hall), to which I bad from 

 the first supposed it to be related. Prof. Lesquereux, to whom I 

 showed the specimens, also supposed the species to belong to 

 Falseopteris of Schimper, which is the same as Archseopteris, 

 Dawson, the name Falseopteris being preoccupied. Some other 

 high authorities on fossil botany, however, have arranged similar 

 forms under the names Asplenites and Adiantites. 



Prom these remarks the student will readily understand that 

 in the present unsettled state of opinion in regard to the limits 

 between several of these older groups of fossil ferns, and the 

 consequent confusion existing in their nomenclature, it is im- 

 possible to determine beyond doubt under what genus this species 

 may ultimately have to be ranged, when all of these questions 

 can be settled. It may therefore have to take the name Sphen- 

 opteris Lescuriana, or Adiantites (Asplenites) Lescurianus. Or, 

 possibly, in case the name Falseopteris of Genitz should be found 

 not to have been based upon a tenable genus, so that Schiraper's 

 name Falseopteris would have to replace Archseopteris, our species 

 may have to be called Falseopteris Lescuriana. 



Specifically this form will be readily distinguished from Cycl. 

 {Archseopteris) Halliana, by wanting the row of broad separate 

 pinnules along its rachis between the pinnae as seen in that species, 

 as well as by its more divided inner pinnules and more rigid pinnae. 

 Prof. Dawson thinks it more nearly related to his G. {Falseop- 

 teris) Rogersi, though, on comparison, he says he finds that the 

 Rogersi has larger pinnae, and more obtuse as well as larger 

 pinnules, and a somewhat different venation. 



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