XXVII.—Further Contributions to our Knowledge of the Fossil Schizæaceæ; Genus Senftenbergia

Until recently the taxonomic and phylogenetic relationships of some of the Carboniferous plants in the two genera, Dactylotheca and Senftenbergia, could not be defined with any clear degree of certainty. The main reason for this was that workers who had investigated these types had failed to reveal some of their most important structural features. In the past, therefore, it has been impossible with the information available to make adequate comparisons of the types included in these genera. In a previous paper the writer (1938) showed that one at least of the three species of Dactylotheca really belonged to the genus Senftenbergia, and demonstrated that it possessed several Schizæaceous characteristics indicating its alliance with the living ferns of that family. In the present work, an analysis of the structural features of the two remaining species of Dactylotheca, and of one species of Senftenbergia has been made. These three plants are Dactylotheca Sturi Sterzel pro. var., Dactylotheca parallela Kidston, and Senftenbergia pennœformis Brongniart. The experiments on the compressions of D. parallela, however, indicate quite clearly that the plant does not belong to either the genus Dactylotheca or Senftenbergia. Its fructifications were found to be of the nature of synangia and were exannulate. Of these two features, the former removes it from Dactylotheca, and the latter prevents it from being classed within Senftenbergia. For this reason D. parallela cannot be included in the Schizæaceæ, and, therefore, the analysis of its structural features is not recorded in this paper.