188 D- H. Scott. 



plants. The anatomical agreement holds good in spite of a con- 

 siderable difference in habit, the fossil stems (known as Ccndopteris, 

 Megapliyton etc. when preserved as casts) having attained arboreal 

 statnre. Quite recently the structure of the Psaronii has been re- 

 investigated hy Eudolf, with special reference to their relation to 

 Marattiaceae, and the result of his researches has been to further con- 

 firm their affinity (Rudolf, 1905). From the evidence of comparative 

 structure and association it appears certain that the Psaronius stems bore 

 the foliage of Fecoptcris, of the same nature as the leaves on which 

 the various synangic fructifications above mentioned have been found. 

 Thus we have to do with a group of plants showing affinity with 

 Marattiaceae, alike in their anatomical structure and in the characters 

 of their reproductive organs. The conclusion appears to be unassai- 

 lable, and yet some doubt of its validity has recently been expressed. 

 Mr. Arber, in his newly published paper „On the Past History of 

 of Ferns" discusses the question and concludes "One fact, however, 

 stands out very clear. The evidence, formerly regarded as beyond 

 suspicion, that the Eusporangiate Ferns formed a dominant feature 

 of the vegetation of the Palaeozoic period has been undermined, more 

 especially hj the remarkable discovery of the male organs of Lygino- 

 dendron by Mr. K i d s t o n. At the best we can only now regard them 

 as a subsidiary group in that epoch of the past history of the Vege- 

 table Kingdom"' (1. c. p. 227j. 



Mr. Kids ton's discovery, here referred to. proves that a tj'pical 

 Crossotheca was borne on the fronds of Splienoptens Hüniwjhausi, 

 which are shown, beyond any doubt, to have belonged, as has been 

 believed for some time, to the Pteridosperm, Lyginodendron Oldhamium. 

 Hence this fructification, which would previously have been classed 

 as Marattiaceous, is now shown to have constituted the pollen-bearing 

 apparatus of a Spermophyte. The Crossofhecas generally (cf. Fig. 17, F) 

 will no doubt prove to have been of the same nature, and this will involve 

 some species of Pecopteris (P. exigua and P. pinncdifida) which, according 

 to Zeiller, should be included under Crossotheca. In this way doubt 

 is cast on a certain number of the supposed Marattiaceous fructi- 

 fications, and we cannot, in the present state of our knowledge, feel 

 sure where the encroachments of the Pteridosperms will stop, especi- 

 ally when we remember Grand'Eury's discovery of the seeds of 

 Pecopteris PlucJceneti Considering the anatomical evidence, however, 

 it seems impossible to doubt that Palaeozoic Marattiaceae actually 

 existed, for the Psaronius type of stem is altogether Fern-like in 

 structure, and presents none of those anatomical features by w^hich 

 the Cycadofilices were recognized, long before the evidence of fructi- 

 fication led to the foundation of the class Pteridospermeae. For the 

 present, therefore, we must continue to accept the existence of a 



