FOSSIL FLORA. 



791 



Eqiiisetnin (lecidnuni ii. s]>. 

 Sequoia laugsdorfii (Bigt.) Heer. 

 .luglans rugosa Lx. 

 Juglaus crescentia u. sp. 

 Castauea pulchella n. sp. 

 Ficns deusifolia u. sp. 

 Ficus asimiua'folia Lx, 



Laurus grandis Lx. 

 Litsea lamareusis n. sp. 

 Platanus guillelmfe Gopp. 

 ELTOdendroii polymorphum Ward. 

 Sapiudus graiidifolioliis Ward. 

 Sapindus wardii u. sp. 

 Aralia uotata Lx. 



Some of these species, as Lygodlum kaulfusii, Castanea pulchella, Laurus 

 grandis, Platanus guiUelmce, Sapindus grandifoliolus, and Aralia notata, are 

 important well-marked species that have weight in showing the close 

 relationships between the floras of tlie two series; but, on the other hand, 

 the perfect distinctness of the beds is shown by the fact that there are some 

 40 species that are confined to each horizon. It will not, therefore, be 

 difficult in future to determine the horizons of the various plant-beai'ing 

 beds within the Yellowstone National Park. 



In order to show how remarkably distinct these three floras are, it will 

 be necessary only to consider the sj)ecies in common between them. As 

 already stated, only 23 forms out of the total of 147 forms are common to two 

 or more of the series of beds. It will not be necessary to present a complete 

 list of these species in common. The numerical results show that 8 forms 

 only are common to the three beds, 2 to the acid and intermediate, and 3 to 

 the intermediate and basic, and, finally, that 10 are common to the acid and 

 basic. When these facts are presented in connection with the total flora of 

 each series, the differences become even more marked. Thus, the lower or 

 acid series, with a flora of 79 species, has only 20 species common to the 

 others. Of these, 8 are common to all three beds, 2 to it and the interme- 

 diate beds, and 10 to it and the upper or basic beds. The intermediate 

 beds, with a flora of 30 species, have 13 species in common with the others. 

 Of these, 8, as above stated, are common to all three, 2 to intermediate and 

 acid, and 3 to intermediate and basic. The basic or younger beds, with a 

 flora of 70 species, have 20 species common to the others. Of these, it is 

 hardly necessary to rejjeat, 8 are common to all three, 3 to it and interme- 

 diate, and 10 to it and acid. These 3 floras are, therefore, shown to be 

 markedly distinct, and it will not be difficult to distinguish them in future. 



