REVIEWS. 
Devonian Fioras: A StuDY OF THE ORIGIN oF CORMOPHYTA. 
By E. A. Newextu ArsBer, M.A., Sc.D., with a preface by 
D. H. Scott, M.A., LL.D., Ph.D., F.R.S. Cambridge, 1/921. 
Price 17s. 6d. net. 
ie forming an estimate of this book it is important to take into 
account the circumstances in which it was published. Dr. Arber 
did not live to complete the work ; he left it in the state of “ a first 
draft which he was never able to revise’. Had he lived to read the 
later memoirs by Dr. Kidston and Professor Lang on the Rhynie 
Devonian plants, he would undoubtedly have modified some of his 
conclusions. Mrs. Arber, who revised the MS., says in a prefatory 
note: ‘“ I do not think that anything in his scientific life gave him 
_a keener intellectual pleasure than the development of the idea— 
the Le:tmotiv of the present essay—that the transition from the 
Ale to the Vascular Cryptogams no longer remains a matter of 
pure conjecture, but that, in the fossil plants of the Devonian 
rocks, we witness, actually occurring beneath our eyes, the passage 
from the Thallophyta to the Cormophyta.” In the preface 
Dr. Scott writes: “ We stand at a new point of departure in our 
theories of the evolution of the higher plants. Arber was one of the 
first to realize this, and his memoir represents a bold and vigorous 
effort to grapple with the problems as they presented themselves to 
him at the dawn of a new epoch.” The publication after Dr. Arber’s 
death of Dr. A. H. Church’s already well-known essay on 
“‘Thalassiophyta and the Subaerial Transmigration”, in which, 
with considerable ability and force, arguments are adduced in favour 
of the origin of land plants from complex types of seaweeds, has 
directed the attention of botanists and geologists to problems of 
evolution having much in common with those discussed in the 
Devonian Floras. These considerations, whether or not readers 
agree with the views expressed, furnish arguments in support of 
the decision to preserve in a permanent form the opinions of one of 
the most devoted students of paleeobotany who ever lived. 
The volume is attractively printed and well illustrated, and an 
admirable portrait of the author is reproduced as a frontispiece by 
permission of the Editors of the GEoLocicat Magazine. During the 
Devonian there were two distinct terrestrial floras, an earlier 
Psilophyton flora and a later Archeopteris flora, differing more widely 
from one another than the Upper Devonian flora differed from that 
of the Lower Carboniferous period. A summary is given of the 
geological age of the several Devonian floras described in a widely 
scattered literature; the inclusion of all the Old Red Sandstone 
plants from Caithness in the Upper Devonian flora is surely incorrect. 
The age assigned to the Caithness beds is not in accordance 
with the views expressed in the Survey Memoir which Dr. Arber 
