246 
Review. 
light of modern scientific method and knowledge, to receive for the 
most part a rational form and explanation in the structure of the 
bi-sporangiate cone. 
Chapter VIII. deals with the young ovulate axis. 
Section IV. comprises the important subject of relationships, 
the heading of Chapter IX. being : “ Existing and Fossil Cycads 
Compared.” It contains a thorough and comprehensive account of 
the distribution, external morphology and anatomy of modern 
Cycads, following on which is a summary of the relationships of 
Cycadeoidese to existing Cycads, the conclusion from which is, as 
regards the vegetative structure, that there is not a single vegetative 
character of the former which does not find a near analogy in the 
latter ; that “ probably complexity of leaf-traces in the line leading 
into the modern Cycads would have been the only difference that 
had yet arisen in the Cretaceous ancestry of the latter in advance 
of the more ancient vegetative features of the Cycadeoideas” ; that 
probably no macroscopic or microscopic feature would have been 
present in early Triassic times in such a type as Anomozamites 
which is wholly absent in modern Cycads ; and that “ the far- 
reaching identity and similarity in the vegetative structures of the 
two Cycadean groups ” could not be “ the homoplastic result of 
physiologic conditions of growth and evolution alone, and merely 
the result of parallel development from two distinctly and remotely 
separated fern-groups.” “ The reasonable hypothesis is that the 
ancestral line from which the Cycadeoidece and existing Cycads 
sprang remained single and homogeneous until the major outlines 
of leaf and stem similarity now common to the two groups were 
established.” The same conclusion is reached from a comparison 
of the reproductive parts. 
The author’s final conclusion is that “the Cycadeoideae, as 
an ancient apposite of the Cycadeae, find their appropriate place 
among the true Cycadales,” inasmuch as he regards the two groups 
as separating off as early as the Permian from a common ancestor 
in the Pteridosperms, which in their turn were derived from a 
closed homogeneous Marattiaceous complex, in which heterospory 
had been evolved. 
The last Chapter, X., is divided into three parts, the first 
treating briefly of the Fern-Cycad relationship; the second of “Sporo- 
phyte Reduction correlated with elimination of separate prothallial 
stages and evolution of seed-bearing quasi-ferns”; the third of 
the “ ultra-relationship of the Cycadalean Gymnosperms (or the 
