DESCRIPTION OF A NEW FOSSIL FERN OF THE GENUS 

 GLEICHENIA FROM THE UPPER CRETACEOUS OF 

 WYOJVnNG. 



By Frank H. Knowlton. 



Custodian of Mesozoic plants, United States National Museum. 



The family Gleicheniacese is undoubtedly a very old one, though 

 there is perhaps still reasonable doubt as to its being quite so ancient 

 as it was at one time believed to be. The genus Gleichenites, so named 

 on account of its supposed affinity to thehving family, was instituted 

 by Goppert ^ for certain fronds from the Carboniferous of Silesia, but 

 this group was evidently composite and the several species have been 

 allocated in Neuropteris, SpTienopteris, Eremopteris, etc., some or all 

 of which are now known to be included in the Pteridosperms. A 

 number of other Carboniferous fronds, such as Mariopteris Zeiller, 

 Diplothmema Stur, etc., on account of their regular, dichotomous, 

 gleichenoid habit of branching, have a more or less strong resemb- 

 lance to the Hving Gleicheniacese, but both these forms are now 

 placed in the Pteridosperms, and the dichotomous branching can 

 not be regarded as estabUshing affinity to the Hving family. Much 

 more important in tliis connection are specimens showing the arrange- 

 ment and character of the fruiting organs, but even when these are 

 present great caution is necessary since the accidents of preservation 

 may render a correct interpretation difficult, if not impossible. Thus, 

 WiUiamson ^ figured from the Engfish Coal Measures a specimen wliich 

 he regarded as the "sporangium of a fern allied to the Gleicheniacese 

 or Schizaeaceae," which certainly appears to possess a complete 

 annulus, but this has been interpreted by later authors as a mistaken 

 observation on an exannulate Marattiaceous sporangium. A much 

 better case appears to be made out for the fruit of Oligocarpia of 

 Goppert (especially 0. hrongniarti Stur), these being smaU ferns with 

 Sphenopteroid foHage bearing circular sori made up of from 6 to 10 

 pyriform sporangia. ZeiUer^ in particular has claimed that they 

 show a complete transverse annulus, and though tliis has been ques- 



1 Syst. Fil. Foss., 1836, p. 181. 



2 Philos. Trans., vol. 167, pt. 1, 1877, pi. 7, figs. 27, 28. 



3 Bassin Houiller du Valenciennes, Flore fossile, 1888, p. 53 et seq. 



Proceedings U.S. National Museum, Vol. 45— No. 1994. 



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