strasbfbgeb's text -book qe botany 357 



pliyta recent and fossil groups are considered together and arranged 

 in live classes — Filicinese, Equisetineae (including the fossil CalamitesJ) , 

 Sphenophyllinae (Palaeozoic), Lj'copodinaeae (including two extinct 

 families, Sigillariaceae and Lepidodendracese), and Pteridospermae, 

 which in the edition of 1908 were regarded as fern-like seed-plants. 

 To these classes the editor has added in a foot-note the Psilophytales, 

 to our knowledge of which he has himself so greatly contributed. In 

 the arrangement of the Angiosperms the Dicotyledons precede . the 

 Monocotyledons, the latter heing regarded as derived N from the Poly- 

 earpic group of Dicotyledons. 



......" A. B. B. 



Devonian Floras : a Study of the Origin of Cormophyta. By 

 Dr. E. A. Newell Arber, with a Preface by Dr. D. H. Scott. 

 8vo, pp. 100, fig. 47. 17s. ijd. Cambridge Univ. Press. 1921. 



The search for origins has a special fascination, and the late 

 Dr. Newell Arber had the happy idea of collecting together our frag- 

 ments of knowledge with regard to the earliest-known land-plants. 

 It was unfortunate that he did not live to complete the generalisations 

 which were based on his survey of the material, and still more that 

 he should not be destined to know of the important discoveries made 

 by Kidston and Lang in the Bhynie Chert and published more 

 recently. As stated in the Preface, however, it seemed to Dr. Scott' 

 that the work was advanced sufficiently far for publication when the 

 author died, and contained a valuable contribution to botanical 

 thought; hence it has been edited by Mrs. Arber and published 

 by the Cambridge University Press. 



In this volume we are provided with an illustrated summary of 

 the fossil plants known from the Devonian rocks and shown some 

 of the weird types which flourished at that remote epoch. This is a 

 worthy task, for the previous descriptions of these plants are scattered 

 through the literature of several countries, and in some cases no 

 modern account of them exists ; thus the only descriptions of some of 

 the Scottish plants of the Old Bed Sandstone are in the original 

 writings of Hugh Miller. 



From the material so exposed, a sketch of the probable origin of 

 these plant-types is given, and this is interesting, even though we 

 may not be able to agree with all of it. The author regarded most, 

 if not all, of the Lower Devonian plants, such as Psilophyton — with 

 which Bhynia is included — as Thallophytes, in spite of their possession 

 of stomata and simple vascular systems. He does not "urge that 

 they were Algae in the sense in which that group is usually defined 

 from a knowledge of its living members," but regards them as 

 probably higher in the scale of complexity, and of a land habit. He 

 does not, however, define what he means by the term Thallophyte, 

 and it would seem a matter of indifference whether we regard 

 them as very complex Thallophytes or very simple Pteridophytes. 

 Dr. Arber was strongly of the opinion that these early types could 

 not be regarded as forms, and his insistence upon their Thallo- 

 phytic nature seems to be based on the feeling that, if classed as 



