August 2, 19CX)] 



NATURE 



315 



liable are fully described and not generally known in 

 this country. 



The complete absence of bibliographic references is 

 a notable defect in the volumes, more especially as they 

 are mainly compilations of the works of other writers 

 aod investigators, whose names appear frequently in the 

 authors' pages. In fact the reader, who might wish to 

 consult the original works, will have great difficulty in 

 knowing where to look for them. We are always glad, 

 however, to welcome any contribution to a literature 

 which is so meagrely represented in our own country. 

 ^^ W. G. M. 



^H PLANTS OF THE PAST, 



^^^^enis de PaUoboianique. By R. Zeiller. Pp. 421. 

 ^^KParis : Carrd and Naud, 1900.) 



^^^OME of the most striking advances in botanical 

 O science during the last two or three decades have 

 been in the domain of PaUeobotany. The study of fossil 

 plants is now generally recognised as a science of primary 

 importance, which affords, not merely useful data for the 

 stratigraphical geologist, but furnishes valuable informa- 

 tion as to the course of plant evolution, and enables us to 

 Ianect some of the phyla of the plant-kingdom at points 

 lere their common origin is clearly indicated. Prof, 

 iller, of the Ecole des Mines, Paris, has played a 

 )minent part in placing fossil botany on a thoroughly 

 entific basis ; his work, which embraces a wide field, 

 characterised by a philosophical handling of facts, a 

 ►roughness of treatment and a breadth of view that 

 i too frequently lacking in scientific writings of the 

 ssent day. In the book before us Prof. Zeiller 

 has performed a difficult task with considerable 

 success. Within a small compass he has included 

 a systematic though necessarily brief account of 

 the more important types of fossil plants, and concise and 

 clearly-written chapters on various subjects of geological 

 and botanical interest. The illustrations are well exe- 

 cuted, and it is a pleasure to note that many of them are 

 new. In the section treating of the preservation of plants 

 as fossils, Zeiller draws attention to a method of examina- 

 tion of " impressions " which he has used with consider- 

 able success. It is often possible, after suitable chemical 

 treatment, to examine microscopically the thin carbon- 

 aceous film, which may sometimes be detached from the 

 surface of a plant fragment lying on a slab of shale, and 

 in this way to obtain important information as to 

 anatomical details. 



Some interesting examples of the Siphone^e are figured 

 and briefly described ; but one or two of the examples 

 quoted, e.g. the supposed Caulerpa from the Kimmeridge 

 Clay, are of very doubtful value. The fossil Myxomycetes 

 of Palaeozoic age, described by Renault and other authors, 

 should be mentioned with a word of caution as to their 

 acceptance as undoubted Mycetozoa. In describing the 

 ! vascular cryptogams, Zeiller notes the danger of attach- 

 ! ing too much importance to the presence or absence of 

 j secondary wood, or to the isosporous or heterosporous 

 character of a genus ; mistakes made in the past, which 

 have persisted for many years, emphasise the need of this 

 Caution. 



NO. 1605, VOL. 62] 



In discussing the systematic position of various extinct 

 generic types of exceptional interest which point to a 

 common origin of'cycads and ferns, Zeiller speaks of 

 the collateral form of the vascular bundles as one o\ 

 those cycadean characters which is met with also in 

 recent ferns. It is, however, important to bear in mind 

 the fact that in. the collateral bundles of Ophtorlossum 

 and other ferns the protoxylem occupies an endarch posi- 

 tion, while the cycadean type of bundle is usually 

 mesarch. 



The chapter on fossil ferns is particularly well done, 

 and contains much that is new. The gtnus Microdictyon, 

 mentioned by Zeiller as a mesozoic fern closely allied to 

 Laccopteris, is hardly sufficiently distinct to be retained 

 as a separate type. 



The enlarged photograph of a leaflet of the well-known 

 " fern," Alethopteris Serlii, given to illustrate the occur- 

 rence of what may possibly be traces of sporangia, does 

 not afford satisfactory evidence that this fern-like frond 

 bore fern-like sporangia. We are still in want of con- 

 vincing evidence as to the nature of the reproductive 

 organs of both Alethopteris and Neuropteris., genera in 

 which the characters of ferns and cycads were com- 

 bined. 



A drawing is given of an exceptionally fine example of 

 a rhcetic fern — Clathropteris piatyphylla — from Tonkin ; 

 as Zeiller has shown, this plant may be compared with 

 the recent genus Dipieris, which, \\V& Matonia pectinata, 

 represents a tropical survival of a widely-spread mesozoic 

 family of ferns. The inclusion of the genus Sagenopteris 

 with the Hydropterideae, rather than with the Filices, is 

 perhaps a little rash, as the evidence so far available as 

 to the reproductive organs is by no means conclusive. 



A good description is given of the genus Spheno- 

 phyllum, but it is to be regretted that exigencies of space 

 prevent full justice being done in this and other cases 

 to the account of anatomical features. Zeiller discusses 

 the possibility of Sphenophyllum having lived as a water- 

 plant in the Coal period forests, but it is perhaps more 

 probable that its long and slender stems were supported, 

 like lianas, by the boughs of stouter trees. 



In dealing with the Calamaries, Zeiller does full jus- 

 tice to the work of English authors, and discusses con- 

 troversial points with admirable judgment and an open 

 mind. The genus Sigillaria is described as a true 

 lycopodiaceous ^plant, agreeing in certain respects with 

 Isoetes. 



In the account of fossil cycads, Zeiller, like other 

 authors, quotes an example of a cretaceous Cycas carpo- 

 phyll, figured by Heer, from Greenland ; the figured 

 specimen, which the writer has seen in the Copenhagen 

 Museum, is not sufficiently well preserved to be deter- 

 mined with certainty, and bears but a distant resemblance 

 to Heer's figure. The genus Podozamites, placed by 

 Zeiller among the Cycads, may possibly be more cor- 

 rectly included in the Conifera;, but it is a type of some- 

 what doubtful position. The flowers of Zamites gtgas, 

 usually known as Williainsonia, mentioned in the section 

 dealing with the Bennettiteie, are usually of Inferior Oolite 

 rather than Lower Lias age. 



Prof. Zeiller gives a useful summary illustrating our 

 knowledge of fossil angiosperms ; as he points out, the 

 literature on Tertiary plants is in urgent need of revision 



