148 THE JOURNAL OF BOTANY 



'poimlnca are Himalayan species ; Liquidamhar orientale occurs on 

 the mountains of Asia Minor ; the genera Sequoia and Carya 

 provide points of contact with the west and east of North America. 

 The evidence on which the conclusions are based is exhibited in 

 twenty well-reproduced plates of slightly enlarged photographs taken 

 by the authors, and the descriptive text is concise and to the point. 



The composition of the Eeuverian flora suggests three streams 

 of migrants from a northern home : two of these made their way 

 to warmer regions, one by w^ay of America and the other towards 

 eastern Asia ; the third stream was less fortunate, most of the 

 migrants being unable to reach a congenial climate along the 

 European route. " Throughout the whole length of Europe and 

 Asia, till the coastal plains of China were reached, the retreat to 

 the south was cut off by one unbroken barrier of seas, deserts, 

 and mountains through which no river opened a way to the south. 

 The want of relationship betw^een the Eeuverian flora and the 

 living flora of Europe would seem to imply that, as w^ave after 

 wave of migration broke against tliis barrier the species it brought 

 must have perished, cut off by the cold of the north behind and of 

 the mountains in front. It was at this barrier that the connection 

 between the present European and the Chinese floras was 

 destroyed ; so that now, except in deposits such as the Eeuverian, 

 and in a lesser degree the Teglian, very little trace of it is to be 

 found." The chain of events that led to the present distribution 

 of the representatives of the Pliocene floras of Europe is clearly 

 outlined in the concluding pages of the account of the Eeuverian 

 plants. As the authors state, it was probably far back in the 

 Tertiary period that the plants which have left their traces in the 

 Pliocene delta-deposits flourished in polar regions, whence they 

 subsequently spread along divergent lines. 



The work of Mr. and Mrs. Eeid affords an admirable example 

 of a combination of qualities, thorough systematic analysis and 

 broad philosophical generalisations. Their success should stimu- 

 late others to take up the study of older Tertiary floras in western 

 Europe, which, though as yet but imperfectly known, show many 

 remarkable instances of the occurrence of American and Eastern 

 types. In conclusion a brief allusion may be made to a few of 

 the Eeuverian species. In naming a new species of Acer A. 

 striatum, the authors have inadvertently employed a specific name 

 previously used for an existing member of the genus. One of the 

 most interesting types recorded is that named Giietum scandens 

 var. rohustum, but the piece of inflorescence-axis on which the 

 identification is founded is hardly convincing. There has been 

 considerable difference of opinion with regard to the presence of 

 Proteaceous plants in Tertiary European floras, and the evidence 

 furnished by detached leaves has generally been regarded as 

 inadequate : it is therefore particularly interesting to find a 

 species of Hakea recorded from Brunssum. The type-specimen is 

 a very small follicle, 7x4 mm., much smaller than the fruit of 

 existing species, but attention is drawn to the fact that unusually 

 small dimensions characterise several Eeuverian seeds and fruits 



