The term Cycadophyta, suggested by Nathorst[1069], is used in a comprehensive sense to include both recent Cycads and the much larger number of extinct types which it is customary to speak of as Cycadean plants or fossil Cycads. The designation ‘Cycads’ in the case of the majority of the fossil forms is, however, open to criticism on the ground that they differ too widely from existing genera to be associated with them in one class. It would be pedantic and inconvenient to give up the almost universal practice of extending the term Cycad beyond the limits defined by the characters of recent species. The important point is to adopt some classification which gives expression to our views as to the degree of affinity between recent and extinct types. In a considerable number of cases, especially impressions of presumably Cycadean fronds and stems that occur without any fertile shoots, it is impossible to determine the degree of relationship to modern types. It was with a view to a rational group-designation for such fossils that Nathorst proposed the term Cycadophyta, including in it the two classes Cycadales and Bennettitales. The Cycadales comprise the recent genera and such extinct types as may legitimately be included in the same class, but as we shall see later there are hardly any fossil species that can be assigned to this section on thoroughly satisfactory grounds. The term Bennettitales is used by Engler, Nathorst, and several other authors as a class-designation for a large number of Mesozoic Cycads agreeing in their more important morphological characters with the Lower Cretaceous stems on which Carruthers[1070] founded the genus _Bennettites_, placing it in a new tribe, the Bennettiteae. Some authors have followed Carruthers in the use of the family-name Bennettiteae for a subdivision of the Cycadales equal in rank to the Cycadaceae, while others, wishing to give greater emphasis to the difference between the extinct and recent plants, prefer to adopt the class-name Bennettitales. Carruthers regarded _Bennettites_ as occupying the same position in relation to other Cycads as _Taxus_ holds with regard to the cone-bearing members of the Coniferae. The adoption of Bennettitales is intended to convey the impression that the class is more distantly related to the recent Cycads than is implied by the analogy of _Taxus_. Nathorst[1071], as the result of his discovery of certain reproductive organs associated with some Rhaetic fronds described as _Dioonites spectabilis_, proposed a third subdivision, the Dioonitales, but he subsequently[1072] restored the fronds to their original designation _Nilssonia pterophylloides_, and on further examination found that the supposed microspore-bearing organs were seeds. _Nilssonia pterophylloides_ would therefore find a more natural place in the class Nilssoniales instituted by Thomas[1073]. BENNETTITALES. =Cycadeoidea.= Buckland.