376 Palaeontologie. 



Cordaiteae, is of the Araucarian type while its primary wood forms 

 mesarch Stands disposed around the pith ; it and Dadoxylon Spenceri 

 are looked upon as links between the Pteridosperms and true Cordai- 

 teae. The most important addition to the account of the latter is the 

 record of a little centripetal xylem in the stem of a specimen frum 

 S h o r e. The affinities of the Cordaitales with the Cycadophyta, Gink- 

 goaceae, and Coniferae have long been recognized and recent work 

 has fully confirmed their affinity with the Pteridosperms. The results 

 of Dr. Wieland's work on American Benettiteae (Cycadeoidea), 

 only vaguely foreshadowed in de first edition, are summarized in 

 the present volume. It is held that many, possibly all, the closely 

 allied European cones were bisexual. Lignier's record of a Liassic 

 form, whose trace appears to have no centripetal wood is also noted. 

 A Short account of the Rhaetic fossil termed by Nathorst William- 

 soiiia angustifolia is added to the description of the Benettiteae 

 which it is thought to resemble in the structure of the cone; its 

 leaves known as Amonosnmites , were small and its habit, unusual 

 in the Cycads or Beitnettiteae, suggests the possibility that it shows 

 a nearer approach to the Angiosperms than any other Mesozoic 

 Cycadophyte. As regards the Cycadaceae proper the evidence for 

 their occurence in Mesozoic rocks remains unsatisfactor^^ doubt 

 having been thrown on the Cycadean nature of Androstrobus. The 

 affinities of the Cycadophyta are more fully discussed. It is held that 

 the Benettiteae and Cycadophyta generally trace their descent 

 through the Pteridosperms. The section dealing with the Conijerae 

 has been considerably altered; forms resembling the Araucariae in 

 reproductive and in vegetative characters are believed to have 

 existed in the Permian. Probable Araucariae occur in the Trias, 

 Rhaetic and Lias, though none are quite convincing until we reach 

 the Jurassic. Jeffrey 's Protodammara from the Cretaceous and 

 Fliehe's Albian Psendoaraiicaria have three and two seeds on a 

 Scale respectively, thus suggesting a possible link between the 

 Araucariae and Abietineae. The short account of the Abieti)ieae has 

 been lengthened by a brief notice of the Jurassic Prepimis, the 

 leaves oi^ which though clearly allied to those of Piiius possess 

 centripetal xylem and other primitive characters, even recalling in 

 some points Cordaitean leaves. Though the Taxaceae have not been 

 certainly traced back beyond the Cretaceous, certain Rhaetic fossils 

 described by Nathorst show points of similarity to Dacrydiiini and 

 Palissya though they may belong to an extinct Gymnospermous 

 race, intermediate between Cycadophyta and Coniferae. Though it is 

 impossible to determine which Coniferous family is the oldest, the 

 Araucariae seem to have the longest geological record, probably 

 overlapping the typically Palaezoic Cordaiteae. The final chapter on 

 the General Result has been completel}^ transformed. As a provisional 

 Classification the vascular plants are distributed under three main 

 heads: the Sphenopsida including the Eqiiisetales, Psendoboruiales, 

 Sphenophyllales and Psilotales ; the Lycopsida consisting of the 

 Lycopodiales only; and the Pteropsida including the Filicales, 

 Pteridospermeae, Gymnosperms and Angiosperms. A certain conver- 

 gence may be traced as we foUow back the history of these main 

 groups; the Sphenopsida show a distinct approach to the megaphylly 

 of the Fern phylum, while anatomicall)'' they approach the Lycopods; 

 the record does not go far back enough to prove whether all 

 Pteridophytes had a common origin, but such a hypothesis is tenable. 

 Palaeontology has thrown no direct light on the ancestr}^ of the 



