Palaeontologie. 229 



and the past floras in the Arctic is more striking than in any other 

 region, and therefore attracts special attention. Among other illustra- 

 tions the case of Juniperus communis is quoted as a warning against 

 too readity assuming that the allied genera in the past must have 

 lived under conditions identical with those now required by living 

 forms. Juniperus for instance is the only living form of the Cupres- 

 sineae to penetrate so far north; if it had been extinct it would 

 naturally have been concluded that it lived under conditions war- 

 mer than is actually the case. But even with the necessary prudence 

 it is certain that in the past the climate of the arctic was warmer 

 than in the present. The difficulty of accounting for this has led to 

 some scientists entirely discarding Heer's results by stating that 

 all his arctic fossils had drifted into place. 



Nathorst therefore points out that each individual deposit must 

 be studied. As a result of detailed work the author summarises the 

 Position for the different horizons. The Devonian system in Bear 

 Island contains roots, showing that part at least of the rieh, coal 

 producing fiora, grew in situ. The Culm of Spitzbergen is cha- 

 racterised by Stigmaria in situ with appendicular organs penetra- 

 ting the clay in all directions. Many other data support the view 

 that the Culm fiora grew in place. 



In the Triassic it is difficult to determine whether the beds 

 are freshwater or marine; but there is nothing to indicate that they 

 came from a great distance. 



The older and newer Jurassic deposits are freshwater, and 

 where, for instance, the surface of the shists are completely covered 

 with leaves of Ginkgo digitata it is strongly suggestive that they 

 grew in situ. 



The Neocomian woods show more accentuated annual rings than 

 those of corresponding age from Europe, and can therefore not 

 have been transported far, but suggest that they lived where the 

 extremes of the seasons were more noted, i.e. practically in situ. 



The Urgonian and Cenomanian floras undoubtedly grew 

 where the fossils are now found; the Senonian may have travelled 

 for some distance, as it is marine. 



A more detailed aecount is given of the Tertiary fiora; many 

 beds indicate freshwater deposits in which plants in situ, or deri- 

 ved from a short distance away, are entombed. 



The conclusion is that in the greater number of cases of plants 

 really grew in the regions in question; and it is therefore evident 

 that the fossil floras of the Arctic should be regarded as the foun- 

 dation of every discussion of the former arctic climates. 



M. C. Stopes (London). 



Reid, C, The Relation of the present Plant Population 

 of the British lies to the Glacial Period. (Naturalist. 658. 

 p. 373—379. 1911.) 



Gives a short history of the attitude of botanists toward the 

 present distribution of the fiora, the author then points out that the 

 Problem has a perfectly definite starting point, and we have "merely 

 to aecount for the incoming of our existing fiora, alter an earlier 

 assemblage had been swept away" — by glaciation. The plant fossils 

 even in Devonshire and the Isle of Wight proving that there 

 was an extreme rigour of climate in the South of England. The 

 author then discusses the suggestions as to possible ways of return 



