Fossil Floras of the Arctic Regions. 225 



A. otopteryx, Gp., occur. In another bed the tuff was formed of 

 cinders and small lapilli, and the way in which the vegetable 

 fragments were embedded leads one to suppose that the branches, 

 leaves, and fruits of the trees were broken off by a shower of cinders 

 and lapilli. A medley of silicified branches of different sizes occurs, 

 and among them are the cones of the Spruce, the nuts of the Walnut 

 (Juglans), and the Hickory (Carya), with the leaves of Ginkgo, etc. 

 In the finer tuffs we likewise find the leaves of the Walnut, the leaves 

 and fruits of an Ash (Fraximis macrophylla, Hr.), and the leaves of 

 species common in the Tertiary flora of Greenland, such as the Plane, 

 Oak, Chestnut, Beech, etc. 



The presence of the leaves of Potamogeton, associated with a fresh- 

 water mussel ( Unio), indicates that the deposits were of freshwater 

 origin. Some of the branches of the trees are silicified and exhibit, 

 under the microscope, an extremely well - preserved structure. 

 M. J. Schuster, who has undertaken a preliminary examination of 

 these remains, concludes that they all belong to one species, which 

 was probably either an arborescent member of the Leguruinosese or of 

 the Kosacese. It is clear that we have here to deal with fragments of 

 vegetation broken off by a shower of ashes and entombed in them, 

 though some fragments may have been transported into a freshwater 

 basin containing mussels and aquatic plants. 



The Tertiary plants discovered by the Norwegian Expedition to 

 Ellesmere Land deserve special mention on account of their state of 

 preservation. They consist almost entirely of branches of Sequoia 

 Langsdorfii, contained in a bituminous laminated clay, from which 

 I have been able to remove them by a process of washing, with 

 the result that they are now isolated like dried specimens in 

 a herbarium. 



I must here bring to a close my review of the ancient plant-bearing 

 beds of the Arctic regions. We may conclude that, in the greater 

 number of cases, it is evident that the plants really grew in the 

 regions in question. Although we know of fossil plants in some 

 marine deposits, as for instance in the Senonian of Greenland, and 

 perhaps also in the Trias of Spitzbergen, these are exceptions which 

 lack importance, since other deposits, of a closely corresponding age, 

 are of freshwater origin. While it may be admitted that, even in 

 Spitzbergen, part of the Tertiary flora may have been transported 

 from a more or less distant country by a river, yet other deposits, on 

 approximately the same horizon, indicate that the greater number of 

 the species, and among them the most important types, have actually 

 flourished in the region itself. 



Taking into account the facts which I have enumerated, it is evident 

 that the fossil floras of the Arctic should be still regarded as the 

 foundation of every discussion of the former climates of this region. 

 How are these favourable climates to be explained ? That is 

 a question to which we are rn>t able to reply at the present moment, 

 and of which the solution belongs to the future. 



DECADE V. — VOL. VIII. — NO. V. 15 



