318 PLANTS, SEEDS, AND CURRENTS 



environment, that is to say, to the present tropical latitudes. With 

 the marked diversity of conditions characterising the later periods, 

 local differentiation of the floras took place in such regions as 

 Australia and South America, which became more or less isolated 

 from neighbouring tropical areas. The Myrtacece underwent 

 " divergent transformations." The fleshy-fruited forms, which, as 

 it is presumed, were nearest to the original types, became character- 

 istic of the warm regions of the globe. Their characters were those 

 common to the numerous genera to which they have given rise, the 

 Eugenias, the Myrtles, the Psidiums, etc. The capsular-fruited 

 forms mark a later adaptation of the fleshy-fruited types to less 

 genial conditions, to poverty of soil and to aridity of climate. They 

 are for the most part Australia's response to the influences working 

 out the differentiation of the Myrtacece, and we see them now in the 

 genera Bceckia, Melaleuca, Eucalyptus, etc. In the successive differ- 

 entiation of tribe and genus Australia, he holds, has played a great 

 part in the history of the Myrtacece. 



There has been no attempt here to summarise a paper which 

 bristles with so many points that it is difficult to handle it. But not 

 the least important part of it is that in which Mr. Andrews throws 

 down the challenge with regard to the older determinations of 

 Eucalyptus in the Cretaceous and Tertiary formations of the northern 

 hemisphere. After pointing out that the history of Eucalyptus is 

 conveyed in the two kinds of leaves which characterise the genus, 

 the earlier opposite leaves telling a story of the warm genial climates 

 that prevailed during the Cretaceous and Tertiary periods, and the 

 later alternate leaves with twisted stalks one of subsequent adapta- 

 tion to the harsher and more arid conditions of Australia, he observes 

 that "it is exactly the later more or less xerophytic and unstable 

 form which has always been reported as existing in the Cretaceous 

 and Tertiary beds of the northern hemisphere, beds strongly sugges- 

 tive of moist, genial climates." Mr. Deane's paper on the " Tertiary 

 Flora of Australia " (Proc. Linn. Soc. N.S.W., 1900) is quoted in 

 this connection, and we are referred to Mr. Cambage's presidential 

 address before the Royal Society of New South Wales in 1913. 



We have to face this objection, which, until it is sufficiently 

 answered, will weigh heavily against our belief in the fossilised 

 Eucalyptus leaves of the north. Yet it would not be antecedently 

 improbable that Eucalyptus should repeat the story of two hemi- 

 spheres, whether in the east and the west or in the north and the 

 south, which is told in varying forms by Liriodendron, Liquidambar, 

 Per sea, Sassafras, Libocedrus, Sequoia, and other plants. When one 

 reflects, as Wallace and many others insist, that ancient and once 

 widespread groups may in our time maintain themselves only in a 

 few widely separated localities, it is not easy for the west and the 

 north to abandon their ancient claim to Eucalyptus. 



In the following year (1914) Mr. Andrews issued a paper written 

 on the same lines concerning the Leguminosce, a paper read before 

 Section E of the British Association in August of that year and 

 before the Royal Society of New South Wales in the following Novem- 

 ber, and here as in his paper on the Myrtacece he expresses his great 



