REVIEWS. 



Fossil Plants : A Text-book for Students op Botany and 

 Geology. By A. C. Seward. Vol. IV : Ginkgoales, Coniferales, 

 Gnetales. pp. xvi -f- 544. 190 illustrations. Cambridge 

 University Press. £1 Is. 



rPHE fourth volume, dealing with the remaining portion of the 

 -*- Gymnosperms, brings to a conclusion this important work, 

 of which the first part appeared in 1898. The main bulk of the plant 

 remains of the past has now been dealt with, but the treatment 

 of fossil Angiosperms has been left for future writers, as the author 

 realizes that a reliable summary of our present knowledge of the 

 geological history of the flowering plants would involve an immense 

 amount of labour, and the co-operation of experts in systematic 

 botany. He considers that he is not adequately equipped for this 

 task, and it would seem probable that it will be long before anyone 

 is found to undertake it, unless one of the American palaeobotanists 

 steps into the breach. 



The whole work has covered the wide and scattered field of 

 palaeobotany in a remarkably thorough way, and almost all the 

 important fossil genera have been mentioned or described, both as 

 regards those based on structural material and those formed for 

 impressions. Brief but excellent summaries of the modern plants 

 to which the fossil types are related have been given, and these have 

 been of considerable utility in giving a conception of the nature 

 of the plants which may be represented as fossils by a group of 

 incomplete fragments ; they also assist in the explanation of the 

 system of classification emi^loyed and indicate what features are of 

 special importance. 



In the volume just pubHshed a full account of the fossil Ginkgos 

 is given. This is of especial interest to the geologist on account of 

 the widespread occurrence of this group in Mesozoic times, as well 

 as owing to the sohtary survivor found to-day in the Maidenhair- 

 tree. It is characteristic of the caution exhibited throughout the 

 work with regard to the multiplication of species, that the first of the 

 190 illustrations in this volume depicts the varied forms which 

 the leaves of the modern Ginkgo hiloba may assume. Some palaeo- 

 botanists consider that Professor Seward is too conservative with 

 regard to species, but it is certainly preferable in a work of this 

 character to keep genera and species united until good grounds 

 can be produced for their separation. For example, in the case of 

 a fossil which is very common on the Yorkshire coast and 

 which often resembles a group of Pine needles, the genus 

 Czekanowskia is defined so as to include forms with entire and 

 bifurcated leaves, on account of their similarity in arrangement 

 on short shoots and also because of the close identity of their 

 epidermal structure. Some palseobotanists would separate the 

 forms with entire undivided leaves into the genus Solenites, but 



