Q66 GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



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

 length 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 undoubtedly very closely related to the living Woocl- 

 ivardia areolata (L.) Moore — so closely, in fact, that it is hardly possible to 

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

 and have identical nervation in both. The only difference is that the 

 mar.gir s of the pinnae 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 much resembles Onoclea sensibilis fossilis New- 

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

 pinnae that are as far apart as it is possible to be. The pinnae are also without 

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

 slightly in producing more elongated areolae in 0. sensibilis fossilis. 



In nervation W. preareolata resembles IF. latiloba Lx., 1 from the Den- 

 ver group, but differs markedly in having the pinnae unlobed. 



Habitat: Northeast side of Crescent Hill, opposite small pond; col- 

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



ASPLEMUM IDDIXGSI \\. Sp. 



PI. LNXIX, figs. 2,3; PI. LXXX, figs. 9. 10. 



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

 pinnae 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, oblong, 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-preserved 

 specimens. It appears to have been a very large fern, possibly several 

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

 largest rachis with pinnae attached is 4 mm. thick, but on the same stone, and 



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



