The “spore-cases” of Dawson may be found to be the microsporangia or perhaps the small seeds of some pteridosperm; the forked axes with a smooth surface and others figured by Miller and by Dawson, with the surface covered with scales suggesting the ramenta of a fern, may be the rachises or rhizomes of filicinean plants. Other specimens may be Lepidodendron twigs, as for example the petrified fragments figured by Dawson as _Psilophyton princeps_; while the stem identified as _P. robustius_ is most probably that of a Gymnosperm. It is doubtful whether a useful purpose is served by retaining the genus _Psilophyton_. It was in the first instance instituted on the assumption, which cannot be upheld, that the abundant material in the New Brunswick beds bore a sufficiently close resemblance to the rhizome and aerial branches of _Psilotum_. _Psilophyton_ has served as a name for miscellaneous plant fragments, many of which are indeterminable. Dr White concludes his account of the genus with the following words[81]: “The examination of such so-called Psilophyton material as I have seen shows the existence in America of two or more groups, represented by several fairly well-marked species which possess stratigraphical value, and which should be carefully diagnosed and illustrated. It is probable also that additional material throwing light on the structure and relationships of these very remarkable early types of land-plants will be discovered at some locality. The inspection of the material in hand emphasises the need, as was pointed out by Solms-Laubach, for the revision of the material referred by various authors to _Psilophyton_, together with a thorough re-examination and re-publication of the types.” Until a thorough re-examination has been made of the Canadian material, with a view to determine whether there exist substantial reasons for the retention of Dawson’s genus, it is undesirable to continue to make use of this name for Pre-Carboniferous fossils which are too incomplete to be assigned with certainty to a definite group of plants. Dr White draws attention to the similarity of some of the Perry basin specimens to Nathorst’s genus _Cephalotheca_[82] from Devonian rocks of Bear Island in the Arctic regions, a comparison which might be extended to other genera and which serves to illustrate the possibility that many of the specimens labelled _Psilophyton_ may eventually be recognised as examples of well defined generic types belonging to more than one group of plants. CHAPTER XIV. LYCOPODIALES.