252 A New Book on Palceobotany. 
be pointed out more clearly that the system of classification of 
these fronds is a purely artificial one, since under the Eu- 
Pecopterideae are included Pecopteris the majority of whose fronds 
are said to belong to the Marattialian alliance though P. Pluckneti 
is a pteridosperm, and Thinnfeldia, whose affinities, though 
uncertain, are almost certainly not filicinean. 
In the section devoted to the anatomical structure of the fern 
groups, a good account appears of the Psaronius types of stem and 
emphasis is given to the view that the variations observed in the 
structure of the leaf-scars and foliar traces of Caulopteris and 
Stipitopteris correspond to differences in level and have little 
systematic importance. Dr. Pelourde has adopted the term 
Botryopterideae (Botryopt^ridees) for the group including the 
interesting Palaeozoic genera of the Botryopteridean and Zygo- 
pteridean type. The rather wider term Coenopterideae, introduced 
by Professor Seward to include this group with its varied forms, 
does not seem to have as yet gained general acceptance, partly 
because some authors seem to consider that a generalised type 
must necessarily exhibit a simple form of structure and regard the 
group as specialised rather than generalised, and also because they 
seem to leave out of consideration the sporangial structure in these 
plants. The more important types in this group are briefly 
described, and in summarising their relations the author adopts the 
views of Kidston and Gwynne-Vaughan with reference to the inter¬ 
relationships of the Zygopteroid forms. The majority of the forms 
are separated into three lines, one headed by Clepsydropis, the other 
two leading through Dineuron to a hypothetical common ancestor 
allied with the primitive Osmundaceae. 
In summarising the ferns it is further pointed out that the 
Palaeozoic sporangia show transitions between the Osmundaceae 
and the Marattiaceae through Discopteris and Diplolabis and between 
the Osmundaceae and Schizaeaceae through Kidstonia and 
Seftenbergia. 
At the end of the book is a short bibliography in which we 
notice that the papers by Professor F. E. Wiess of Manchester are 
mingled with those of the late Prof. C. E. Wiess of Berlin without 
distinction. 
In spite of the criticisms made above the present work is 
undoubtedly a very useful little volume, and gives a good survey of 
the fossil pteridophytes in a small compass. At the very modest 
price of five francs it should find its way into the libraries of many 
English botanists, and we look forward to the appearance of the 
two remaining volumes. 
