58 F. H. KnowUon — Tertiary Floras^ etc. 



The cryptogams appear to have been a much more prominent 

 floral feature during Tertiary times than now. Of the two 

 orders present, the Filices and Equisetacese, the former is repre- 

 sented by ten and the latter by four species, while the living 

 flora has but six ferns and four horsetails, all of which are 

 rare. 



The ferns were abundant. They belong to six genera and 

 are represented in several cases by a large number of speci- 

 mens. The largest genus is Asplenium with four species. 

 One of these that has been described as new is perhaps the 

 largest and finest that has been detected outside of the 

 Carboniferous, at least in l^orth America. The genus Aspi- 

 dium is represented by two species, both of which appear to 

 have been rare. They are, however, both fruiting, a condition 

 of uncommon occurrence among fossil forms. There is also a 

 fine Woodwardia that appears to be quite closely allied to a 

 species now living in the eastern United States, and beautifully 

 preserved examples of the widely distributed climbing fern 

 {Ly g odium Kaulfiisii). It is very similar to the only living 

 North American species L. jpalmatur}%. The other ferns are 

 an Osmunda and a delicate form referred provisionally to the 

 genus Davallia. 



The genus Equisetum, although represented by four more 

 or less satisfactory species, was not abundant or particularly 

 important. The commonest form is small and has much the 

 appearance of the living F. limosum. 



From what has been presented, it is obvious that the present 

 flora of the Yellowstone National Park has comparatively 

 little relation with the Tertiary floras, and can not be consid- 

 ered as the descendant of it. It is also clear that the climatic 

 conditions must have greatly changed. The Tertiary flora 

 appears to have originated, or at least to have had its affinities 

 at the south, while the present flora is evidently of northern 

 origin. The climate during Tertiary time, as made out by the 

 vegetation, was apparently not unlike that in some parts of 

 the southern United States at the present day. 



It would be of interest to describe the remarkable fossil 

 forests of standing trunks, but their consideration must be 

 deferred to the final report. 



