242 
Review. 
It is true that in Fossil Botany some leeway has been made up 
in recent years, and unknown families and even classes have been 
reconstituted. But if the rate of progress has been temporarily 
accelerated, we cannot on that account expect—what seems so rare 
in analogous cases—that all our missing links should coma 
conveniently to hand. We shall have to rest content to draw such 
conclusions as we may from an increasing knowledge of the range 
of structure of the great groups as they succeed one another in 
time. Judged by this modest standard, our knowledge of the main 
phases in the phylogeny of the higher plants has advanced 
amazingly, and it may be possible in the not very remote future to 
trace with some confidence the main lines that have been followed 
by the Angiosperms in the hitherto obscure process of their 
evolution. 
AMERICAN FOSSIL CYCADS. 
R. G. R. WIELAND’S years of industrious labour on the 
Mesozoic Cycads are at last culminated by the publication of 
a work, the interest, beauty and importance of which it is difficult 
to over-estimate. 
After the knowledge we possess of modern living Cycads and 
the recent detailed information to hand as to the nature of their 
Palaeozoic ancestry, the Pteridosperms, what could be more oppor¬ 
tune than this timely appearance from America of a fund of 
instruction with regard to the character of plants pertaining to the 
same great group, but occupying the vast time-period which we call 
the Mesozoic, intervening between the Palaeozoic and the modern 
epoch. 
The Mesozoic Cycads, known in America as the Cycadeoidea? 
and in this country as the Bennettiteae, possess features of extra¬ 
ordinary interest and uniqueness which mark them outasbelongingto 
a distinct and independent line of evolution among the Cycadophyta. 
Nevertheless, they exhibit characters which clearly relate them on 
the one hand to modern Cycads and on the other to the ancient 
Pteridosperms. 
In the introductory chapter Dr. Wieland affords us an excellent 
account of the various discoveries and collections of the Cycadeoideae, 
an account which reveals the world-wide distribution of the group 
during the Mesozoic period, 
