84 Revieivs — Fossil Pl(Mits. 



though, this course has not been followed, the view is mentioned 

 and references are given which will enable the student who is 

 interested to investigate the matter for himself. 



Several Palaeozoic genera, such as Psygmophyllum, which have 

 been assigned by various authors to the Ginkgoales are described, 

 but it is pointed out that the evidence on which this classification 

 is based is wholly inadequate. 



A considerable section of the book is devoted to the consideration 

 of fossil coniferous woods, a subject which badly needed summarizing 

 in a broad comprehensive way, and which has also been dealt with 

 by Kraiisel in a current number of Palceontographica. The majority 

 of the pre-Tertiary petrified woods are of Coniferous affinities ; they 

 are by no means uncommon, but their identification has presented 

 many difficulties in connexion with the characters to be used and 

 in their nomenclature. Several previous authors have dealt with 

 groups of woods of a particular age or from a particular region, 

 but a recent comprehensive summary was lacking. The present 

 descriptions and classification ought to be of great assistance to 

 those who wish to determine fossil woods, without making a special 

 study of the recent and fossil forms and reading through the 

 extensive literature on the subject. 



The study of fossil coniferous twigs and of the remains of cones 

 has also been greatly assisted by the succeeding chapters. Some 

 forms, such as those from the American Cretaceous had been 

 thoroughly investigated, but a vast mass of unsystematized informa- 

 tion existed in botanical and geological literature about other types. 

 The student is invariably puzzled to find Permian twigs described 

 as Walchia, while apparently similar types from the Trias are known 

 as Voltzia and from the Jurassic as Pagiophyllum or Elatides. The 

 summaries of the characters of the twigs and cone structures upon 

 which these generic distinctions are founded, will be a great help to 

 both students and investigators, and should assist in standardizing 

 our nomenclature. The examination and criticism of all the evidence 

 by an author who is an enthusiastic student of the recent Coniferse 

 means a considerable step forward in our knowledge of fossil plants 

 and of the past history of the cone-bearing trees. 



The title of student has just been aj) plied to the author of this 

 monumental work, and it is to students in the widest sense of the 

 word that this textbook will appeal. Parts of it will be of great 

 value to the elementary student who is making a first acquaintance 

 with the principal fossil types, bi^t as a whole the work will be 

 invaluable to all who are engaged in a study of the vegetation of 

 past ages. The very copious references to original papers, to 

 discussions, and to the best figures will be of immense help to all 

 who are interested in this great field of knowledge. The list of 

 works referred to in vols, iii and iv which is printed at the close 

 of vol. iv occupies fifty-one pages, and indicates the extent of the 

 literature which has been used in the compilation of this book. There 



