OF UPPER EOCENE CLIMATES. 9 



there is a single Equisetum instead of two species; the four species 

 of Feildcnia represent but a single botanical species, of still unknown 

 botanical affinity; the five pines represent a less number of species, 

 and were named by Heer before the old genus Pinus was segregated ; 

 the two Phragmites represent leaf fragments of grasses or sedges, 

 and nothing more definite, and the Caulinites is a sedge or grass root- 

 stock, while other leaf fragments are named Carex. Iridium and 

 Salix represent absolutely nothing determinable, as Heer practically 

 admits in his discussion of them ; the two species of Corylus described 

 represent but a single species, to which what Heer called Alnus should 

 also probably be referred ; the Ulnius is also a Corylus, in my opinion ; 

 the Viburnum is a Populus; and the Tilia is a Corylus. These sug- 

 gested changes may be merely a matter of opinion, they certainly are 

 my opinions, but the suggested revision is no essential part of my 

 argument. 



Revised as suggested in the preceding paragraph, the result is : 

 Equisetum, Feildenia, Thuites, Tax odium, Pinus, Abies, sedge or 

 grass fragments, Populus, Betula, a variety of Corylus leaves, and 

 apparently a fragment of a Nymphaa rootstock. Considered in this 

 attenuated form this flora is still remarkable enough. The flora in 

 the immediate vicinity of Cape Murchison under the climatic condi- 

 tions of the present includes Carex, various grasses, and the genera 

 Salix and Vacciniufii. The present isotherms would have to swing 

 15 to 20 degrees northward to permit the existence of such an Eocene 

 flora as that listed above in Grinnell Land. The dwarf birch of the 

 present reaches the latitude of Grinnell Land in Spitzbergen ; and 

 white birches occur north of the Arctic Circle in Europe, Asia, and 

 North America, or within about ten degrees of the Grinnell Land 

 fossil flora. 



The significant feature about these Eocene Arctic floras is that 

 they show a comparable northward swing of not alone their northern 

 limits, but also of their southern limits, which in turn is comparable 

 to the northward advance of the Jackson flora that I have considered 

 to be of the same age. The Jackson flora reaches Latitude 37° 

 North. The most similar existing flora to that of the Jackson does 

 not extend above Latitude 26° North, and then only under especially 



