88 REVIEWS 



Devonian Floras. By E, A. Newell Arber. Cambridge: Uni- 

 versity Press, 1 92 1. 



The author lays down an essential distinction between the early and 

 the later Devonian floras, and discusses the geological age and distribu- 

 tion of the two. The older is called the Psilophyton Flora, and the 

 later, the Archaeopteris Flora, in accordance with the predominant 

 plant types. Among the fossils of the Lower Devonian flora are the 

 newly discovered types from Rhynie in Scotland which are at present 

 the earliest known land plants. 



Arber examines in detail the geologic age of different Devonian plant 

 beds, taking into consideration only well-known floras ot. which the hori- 

 zons have been more or less satisfactorily determined. He is inclined 

 to accept a highly polyphyletic h)rpothesis with regard to the origin of 

 the main groups of vascular cryptogams which he thinks to be derived 

 severally from distinct algal types. He realizes that we are at a new 

 point of departure in our knowledge of the evolution of higher plants, 



and his book is written from this point of view. 



A. C. N. 



A Catalogue of the Mesozoic and Cenozoic Plants of North America. 



By F. H. Knowlton. United States Geological Survey, 



Bulletin 696, Washington, 1919. 

 The book is a new edition of A Catalogue of the Cretaceous and Terti- 

 ary Plants of North America, much enlarged and supplemented. It 

 includes the whole of the Mesozoic as well as the Cenozoic of North 

 America, exclusive of Greenland and Mexico. The larger portion of the 

 book is an alphabetical catalogue of plants to which is added a biologic 

 classification of genera, an index of genera and families, and floral lists 

 of plant-bearing formations. In his Introduction, Knowlton includes a 

 table which gives the approximate stratigraphic position of plant-bearing 

 beds, to which are added a few well-known non-plant-bearing marine 

 units so that their relative positions may be seen. 



The catalogue is one of the most useful books published on the North 

 American fossil floras. A similar catalogue of the Paleozoic plants of 

 North America is much to be desured. There is only one man who can 



Write it — ^Dr. David White. Will he give it to us ? 



A. C. N. 



