94 



BOTANICAL GAZETTE [january 



We should have treated the Pteridospermae, Cycadophyta, and Cycadales 

 together as a cycadophyte phylum. The Cycadofilices, including fernlike plants 

 which may belong to the Pteridospermae but in which seeds have not yet been 

 discovered, naturally follow the known Pteridospermae; but it does not seem 

 natural to treat the Cordaitales between the Pteridospermae and the Cycado- 

 phyta. After a careful reading of the Pteridospermae, we still fail to see why 

 they should not be regarded as an order of the gymnosperms rather than as a 

 group of equal rank. However, these are minor and very insignificant objec- 

 tions. The book is full of detailed descriptions and critical discussions which 

 will make it possible for investigators with far less training than Seward to make 

 valuable studies of such material as may fall into their hands. 



The Pteridospermae are introduced by an excellent description of Lyginop- 

 teris, the name applied to the plant whose various fragments have been described 

 under the names Lyginodendron (stem), Sphenopteris (leaf), Lagenosloma (seed), 

 Crossotheca (microsporophylls) , and Kaloxylon (root). The descriptions of 

 Heterangium and Medtdlosa, while less complete, give a critical account of what 

 is known up to date. The presentation of these 3 forms, with comparatively 

 fragmentary accounts of others, shows where research is needed, and will enable 

 students to fill in missing phases of life histories as material becomes available. 

 In all the paleozoic forms of the cycadophyte phylum, information in regard to 

 to the gametophytes and embryo, although very desirable, is very scant; but if 

 attached seeds could be found and sectioned, the preservation seems good enough 

 to show the desired features. 



The treatment of the Bennettitales (Cycadophyta), although it occupies 

 226 pages, seems short in comparison with the big volumes of Wieland. The 

 English and French contributions to our knowledge of this group are presented in 

 considerable detail, and the author has drawn upon Wieland for numerous 

 excellent figures. If well-preserved reproductive structures of the lower mem- 

 bers of this group, especially Williamsonia, could be found and sectioned, the 

 results could not fail to be important, for they would ahnost certainly throw 

 light upon the origin of the living cycads. 



The Cordaitales, representing the coniferophyte phylum, do not occupy so 

 much space, but comparatively little is known about the group. If our knowl- 

 edge of these forms were as complete as in case of the Bennettitales, a treatment 

 of the Coniferales would be much simpUfied. As it is, the various stems, leaves, 

 and reproductive organs referred to this group are described under their respec- 

 tive categories, and material is thus accumulating for a connected life history. 



The chapter on paleozoic gymnospermous seeds is particularly conservative 

 and interesting. Many morphologists would have felt little hesitation in assign- 

 ing most of these seeds to one group or to another, but Seward, throughout the 

 work, recognizes the danger of being too positive when dealing with unattached 

 fragments. The characters of the various types of seeds are described and dis- 

 cussed. Although some knowledge of the internal structure is available, it is 

 very evident that little is known in regard to the gametophyte. A knowledge of 



