210 D. H. Scott. 



liave belonged to seed-bearing plants, as already indicated by the 

 Crossotheca fructification wliicli some of them bore; it is however ex- 

 tremely probable, as pointed out in discussing the Palaeozoic Ferns, 

 that the form-genus Pecopteris is an altogether heterogeneous as- 

 semblage, including plants almost as remote from each other as 

 Stangeria is from Lomaria, with which it was once confounded. Some 

 of the Palaeozoic plants with the Pecopteris habit may well have 

 been true Ferns of Marattiaceous afflnitj^, though others Avere un- 

 doubtedly Fern-like Spermophyta, 



Systematic Position of the Pteridospermeae. 



When Prof. F. W.Oliver and I suggested, in 11)04, the foundation 

 of a distinct class Pteridospermeae, we provisionally defined the pro- 

 posed class "as embracing those Palaeozoic plants, with the habit 

 and much of the internal organization of Ferns, which were repro- 

 duced b}' means of seeds''. We deliberately abstained from attempting 

 a more exact definition, and our caution was justified, for one of the 

 characters which then seemed of some value as a criterion, the radial 

 symmetry of the seed, has already proved not to hold good. Where 

 the anatomical structure is known, as in Lyginodendreae and Me'- 

 dulloseae, the provisional definition, though vague, is quite serviceable. 

 In the case of specimens only known as yet in the form of im- 

 pressions (such as Aneimites fertilis and Pecopteris Plucliencti) we have 

 to rely on the Fern-like habit alone in referring the plants in 

 question to Pteridospermeae rather than to Gymnosperms proper. Such 

 difficulties are unavoidable in palaeontological work; we have to do the 

 best we can with such characters as are available. We may, however, 

 now that our knowledge has somew^hat widened, consider the position 

 of the Pteridospermeae rather more closely. 



The name Cycadofilices designated a group, only known at the 

 time by its vegetative characters, which hovered in the gap between 

 Filicineae and Cj'cadophyta without showing an}' decided leanings to 

 either side. The class-name Pteridospermeae represents a more ad- 

 vanced stage in our knowledge, and indicates plants which w^e know 

 to have been already definitely Spermophytic, though retaining many 

 marks of a Filicinean origin. This consideration appears sufficient 

 to justify the institution of the new class. 



The question remains, w^hether the Pteridosperms should be in- 

 cluded under Gj'mnosperms or kept apart, at least for the present, 

 as a Sub-Kingdom of their own. Many botanists will doubtless follow 

 Prof Zeiller in choosing the former alternative — personally', I incline 

 to the latter, for reasons which I will now state. The question, it 

 may be said at once, is largely one of convenience, for there can be 



