606 GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



alternate — that is, are the same distance apart. They are at least 6 cm. in 

 leno-th and '2 cm. in width. The full length and form of the apex could not 

 be determined. The nervation is well shown in the figure. 



This species is undouljtedly very closely related to the living Wood- 

 wardia areolata (L.) ^loore — so closely, in fact, that it is hardly possible to 

 separate them satisfactorily. The pinniB are alternate, of the same shape, 

 and have identical nervation in both. The only ditferent-e is that the 

 marr^irs of the pinna? are entire in the fossil and more or less serrate in the 

 living species. It is possible that more material of the fossil form would 

 show differences in this respect and bring them absolutely together. 



This new fossil species nuu-li resembles Onoclea sensihiUs fossilis New- 

 berry, from the Fort Union group, but it differs in having strictly alternate 

 pinnse that are as far apart as it is possible to be. The pimia? are also without 

 lobes of any kind, being only slightly undulated. The nervation differs 

 .sliii'htlv in producing more elongated areola? in 0. sensibiUs fossilis. 



In nervation W. preamohda resembles TI". hdiloha Lx.,^ from the Den- 

 ver group, but differs markedly in having the pinna" unlobed. 



Habitat: Northeast side of Crescent Hill, op})o.site small pond; col- 

 lected by F. H. Knowlton and G. E. Culver, August 2, 1888. 



ASPLF.NIUM lUDINGSI U. .Sp. 

 PI. LXXIX, tigs. 2.3; PI. LXXX, ligs. 0.10. 



Frond large, at least twice pinnate; main rachis thick, slightly zigzag; 

 pinna? alternate, remote, standing at an angle of 30° to -45°, long-lanceolate, 

 tapering to a rather slender apex, rachis strong, often abruptly curved 

 upward, cut into numerous alternate, oljlong, obtusely-acuminate pinnules 

 with upward-turning points; nervation of pinnules simple, consisting of a 

 slender midnerve and about 9 pairs of unforked, close, parallel branches, 

 which are slightly arched forward in passing to the borders; sori oblong, 

 nearer the margin than the midnerve. 



This fine species is represented by a large number of well-jjreserved 

 specimens. It api)ears to have been a very large fern, possibly several 

 times pinnate, but none of the specimens show the larger connections. The 

 largest rachis with pinnje attached is 4 nun. thick, l)ut on the same stone, and 



'Tert. Fl., p. 54, PI. Ill, figs. 1, la. 



