570 Reviews — Dr. D. E. Scott— Studies in Fossil Botany. 



paljeontologist lias to deal. The group contains ferns belonging to 

 several 'genera' as determined by the impressions of their fronds, 

 for we find members of the Brongniartian genera Sphenopteris, 

 Alethopteris, and Neiiropteris among the Cycadofilices. Sphenopteris 

 Sbninghaiisi is the frond of Lyginodendron Oldhamium, and M. Eenault 

 has shown that the petioles of certain Alethopteris and Neuropteris 

 have the structure of Ifyeloxylon, which in turn has been found 

 attached to the stem of Medullosa, one of the Cycadofilices. 



In dealing with these interesting plants, Lyginodendron Oldhamium, 

 one of the monostelic forms, is first described. It is treated very 

 fully, the stems, branches, roots, and foliage being very common 

 in the 'Coal-balls.' The only point of interest unknown is its 

 fructification, which, however, Dr. Scott presumes may have been 

 Calymmatothecous, as shown in his restoration in the frontispiece. 

 The evidence on which Dr. Scott arrives at this conclusion is derived 

 from the reference to Sphenopteris (Calymmatotheca ?) Stangeri, Stur, 

 of a Calymmatothecous fructification, and his belief that this fern is 

 specifically identical with Sphenopteris Honinghausi — a view we are 

 unable to share, as we regard these two species as essentially distinct. 



Lyginodendron — or perhaps better, Lyginopteris Oldhamia, as re- 

 named by Potonie — is followed by a description of Heterangium, 

 another monostelic form with Sphenopteroid foliage, at least in the 

 case of LL. Grievi. Calamopitys Saturni, whose generic name gives 

 a very false idea of its true position, the Cycadoxylece, and Protopityece, 

 are next considered, and these lead us up to the genus Medidlosa, the 

 type taken for description being the Medullosa anglica, Scott, the 

 oldest known member of the genus, and one possessing a less 

 complex structure than those occurring in later Carboniferous rocks. 

 Medullosa exhibits a polystelic type of structure. All the Cycado- 

 filices show the remarkable character of a normal development of 

 secondary bast and xylem. The fern petioles originally named 

 Myeloxylon are now known to belong to Medullosa. The complex, 

 organization of these ferns has been worked out in admirable detail, 

 and the occurrence of cycadaceous characters in association with the 

 fern type of structure is fully dwelt on. 



The Poroxylon and Cordaitece fall to be considered in Lecture xii. 

 The Cordaitece are only now beginning to be understood. Some 

 species of so-called Araucarioxylon, which must be referred to the 

 Cordaitece, have been shown to possess a primary wood arranged in 

 a circle round the periphery of the pith. For our knowledge of the 

 structure of the flowers of Cordaites we are indebted to M. Eenault, 

 ■who has worked them out in great detail. The anatomy of the 

 leaves and roots is also known and described. The position of 

 Cordaites seems to lie between Cycads and Conifers, though at the 

 same time it holds individual characters which prevent it being, 

 united with either. 



Lecture xiii gives an account of the Mesozoic Gymnosperms, and 

 Lecture xiv is devoted to the "General Eesults" derived from the 

 foregoing course of study. The last lecture is therefore in some 

 respects the most important of all, for it gives us the conclusions- 



