May 11, 1883.] 



SCIENCE. 



397 



FOSSIL BOTANY. 



Cours de botanique fossile fait au Museum d^histoire 

 naturelle. Par M. B. Renault. 2eme annee. 

 Paris, Masson, 1881. 194 p., 24 pi. 8°. 



In the first volume of this remarkable work, 

 which was reviewed in this countrj^ a j'ear 

 since (Proc. Amer. phil. soc), the author has 

 exchisiveh' considered the Diploxyleae, and 

 given the historj' of each of the families of 

 that class, — the C^'cadeae, Zamiae, Cj'cadox- 

 yleae, Cordaiteae, Parosjdeae, and Sigillariae. 

 As the question of the relation of the Parox- 

 3'leae and Sigillariae is of the greatest impor- 

 tance for the histor}' of the evolution of plants, 

 it has been considered again in this j-ear's 

 course, though, in the preceding, the structure 

 of the Sigillariae had been alreadj' examined. 

 The author therefore proposes to stud_y the most 

 highly organized vascular cryptogams, and to 

 search bj^ studying the anatoraj' of the stems, 

 the branches, and the roots, if, as has been as- 

 serted, anj- of them, at a certain point of their 

 existence, take on the phenogamic character so 

 distinctlj^ that a separation of these two great 

 divisions becomes impossible. 



The essential characters of the vascular cryp- 

 togams to be examined are presented in a 

 table. They are divisible into two prominent 

 groups : 1°. The Lj-copodiaceae and the Rhizo- 

 carpeae, which are heterospores, though some 

 L3"copodiaceae are both heterospores and iso- 

 spores ; 2°. The Ophioglosseae, the Equise- 

 taccae, and the ferns, which are isospores. 



The first group of the Lycopodiaceae is that 

 of the Lepidodendreae. beginning in the first 

 chapter with the genera Psilophiton and Lepi- 

 dodendron. Chapter 2 examines in detail the 

 anatomical structure of three types of Lepi- 

 dodendron ; viz., L. Rhodumnense, L. Har- 

 courti, and L. Justieri. Chapter 3 relates to 

 the anatomj' of the fructification of Lepido- 

 dendron or to the Lepidostrobi. Chapter 4 

 gives a brief examination of the characters of 

 the other genera referred to the Lycopodiaceae. 

 Chapter 5 compares the distinctive characters 

 of Sigillaria and Lepidodendron, the differ- 

 ences, after discussion, being set forth in a 

 comparative table ; the Sigillariae being recog- 

 nized as related to the phenogamous plants, 

 and the Lepidodendreae to the Lj-copodiaceae. 



To the Ehizocarpeae belong, at the present 

 epoch, the genera Pilularia, Marsilia, Salvinia, 

 and Azolla. Of these, no remains have been 

 found in the carboniferous ; but species of the 

 genera Sagenaria and .Sphenophjdlum seem to 

 be related to this familj'. The history of the 

 genus Sphenophj'llum, as heretofore known, 



and the description of the species, are given 

 in chapter 6. The anatomical structure of 

 Sphenophyllum is discussed in chapter 7 ; the 

 wood}' axis is always full, not hollow, and 

 inflated at the articulations only when a branch 

 is formed ; the stems, the leaves, the bark, the 

 roots, the fructification, are treated. 



With chapter 8 begins the treatment of the 

 cryptogamous isospores, which may be sum- 

 marized as follows : Equisetaceae. — The liv- 

 ing plants of this family have onlj' one kind of 

 spores ; examination of the stems and other 

 organs. Asterophyllites. — Tiges, branches, 

 and principal species described ; two forms of 

 fructification described (Wolkmannia and Ma- 

 crostachj-a) . Chapter 9. Annulariae. — De- 

 scription of the different organs ; stems, 

 branches, and fructification ; and of the spe- 

 cies. Chapter 10. Fructification of Annu- 

 laria, considered with species of uncertain 

 relation (Bruekmannia and Cingularia) . This 

 chapter ends with a comparative table expos- 

 ing the characters of the AsterophyUiteae and 

 the Annulariae. Chapter 11 contains descrip- 

 tions of the genera Schizoneura, Phjdlotheca, 

 and Equisetum. Nine species of Schizoneura 

 and twentj^ of Equisetum are described, none 

 from the paleozoic formations. The genus 

 Calamites and its different organs are described 

 in chapter 12. 



The concluding chapter contains a table 

 showing the different formations where the 

 plants described in the volume have been ob- 

 tained. The true Equisetaceae do not appear 

 lower than the trias. The range of Astero- 

 phyllites, Annularia, Calamites, and the Lyco- 

 podiaceae, is from the upper Permian to the 

 culm or subcarboniferous measures ; that of 

 Psilophitum is in the Devonian and upper Si- 

 lurian. The volume ends with considerations 

 on the distribution of the plants, on the 

 climate as indicated by their nature, and on 

 certain organs which may be useful in classifi- 

 cations. It would be useless to eulogize this 

 excellent work, which is illustrated with twenty- 

 three splendid plates. The above summary 

 suflSciently shows its importance. 



A NEW CALCULATION OF THE ATOMIC 

 WEIGHTS. 



Die atomgewichte lier elemente, aus den originalzaJden 

 neu berechnet. Von Dr. Lothak Meyer und 

 Dr. Karl Seubert. Leipzig, 1883, Breitkopf 

 ^ Hcirlel. 246 p. 8°. 



The great importance to chemistry of an 

 exact knowledge of the atomic weights is well 

 illustrated by the recent activity of chemists in 



