JRevieivs — Clement Reid — Origin of the British Flora. 427 



fact points rather to the need of further investigations such as 

 Clement Eeid has so ably conducted, than to the absence of eo 

 many existing species from the Pleistocene vegetation. Only six 

 exotic species have as yet been discovered. As the author suggests, 

 the number of such plants in the Pleistocene flora was no doubt 

 much greater, but the difficulty of obtaining suitable material as an 

 aid to the identification of seeds seriously hampers the recognition of 

 extra-British species. The book concludes with a most valuable 

 list of the plants so far obtained from deposits varying in age from 

 Pre-Glacial to Roman, and it is comforting to find that the botanist 

 may confidently consult the list as one which is very largely based 

 on the determinations of a highly competent specialist. 



On first turning over the pages of Mr. Reid's volume, the reviewer 

 was glad to find what he at first took to be a bibliography of works 

 referred to in the text, but on closer inspection he discovered that 

 the publishers had utilized the end of the book as an advertisement 

 of " Books and Pamphlets on British Botany, offered for sale at 

 net prices." A list of papers dealing with Post-Tertiary Geology 

 and Botany, including such works as Warming's excellent memoir 

 on (Ecological Botany and others on the distribution of plants,, 

 would have been a useful addition. 



As already pointed out, Mr. Eeid's book bears the stamp of 

 careful and accurate work of the greatest merit ; but one feels 

 a little disappointed that he has not given a concluding chapter 

 summarizing in a readable form the evidence at present available 

 from which to draw conclusions as to the origin of the British Flora. 

 Practical hints and suggestions as to the most promising lines of 

 research would have added not a little to the value of the work 

 as an incentive to geological and botanical investigation. One 

 closes the book with a wish for more, and while congratulating the 

 author on his sensible resolve to be as concise as possible and to 

 restrict himself to sure ground, it may be fairly urged that a second 

 edition would benefit by greater fulness and by the addition of one 

 or two more chapters. 



It may be asked to what extent does this memoir advance our 

 knowledge as to the origin of the British Flora ? The title of the 

 book is perhaps somewhat misleading : the facts it contains may be 

 compared with documents of supreme importance in the construction 

 of a complex genealogical tree ; there is much additional evidence 

 which we may reasonably hope to obtain, but much also that we 

 can never discover. The merit of this welcome contribution to our 

 knowledge is, that the evidence it presents is of the highest value, 

 because it is thoroughly trustworthy. To understand the gradual 

 evolution of the British Flora as it exists to-day, we must con- 

 siderably extend our retrospect beyond the period from which 

 Mr. Eeid begins his survey, when practically all the plants seem 

 to have been identical with existing species. Without reflecting on 

 the value of the work, it may be truly said to furnish us with data, 

 much fuller and more valuable than any previously available, towards 

 the compilation of the past history of our native plants ; but in itself 



