SUMMARY ON THE PTERIDOSPERMS 471 



Summary on the Pteridosperms 



We have now completed our sketch of those Fern- 

 like Palaeozoic plants in which there is reason to believe 

 that seeds were produced. Direct and conclusive 

 evidence is still limited to a few instances, but these 

 few are widely distributed. The fully established cases 

 of Lyginodendron oldhamium, Neuropteris heterophylla, 

 Aneimites fertilis, and Pecopteris Pluckeneti represent 

 four distinct families, 1 in each of which there is further 

 a considerable body of collateral evidence, varying in its 

 degree of cogency, but all pointing the same way, so as 

 to leave no doubt that the seed-bearing habit was very 

 widely spread. Fragmentary as our knowledge at 

 present is, it is sufficient to establish a strong probability 

 that a large majority of the Fern-like plants of Palaeozoic 

 age were Spermophytes. 



It is obvious that it would be altogether premature, 

 in the present rudimentary state of our knowledge, to 

 attempt to define the limits of the Pteridospermeae or 

 to assign them precise characters. As regards the 

 extent of the Class, it no doubt embraced most of the 

 Neuropterideae and Sphenopterideae, a considerable 

 part of the Pecopterideae, and various outlying genera, 

 such as Aneimites and Eremopteris. It is impossible 

 to tell how much further the limits of the group may 

 be extended by further research. Equal caution is 

 necessary in attempting to draw up the characters of 

 the Pteridospermeae, for it is only in comparatively 



1 Aneimites (Adiantites) was placed by Professor Zeiller, on account of 

 its frond-characters, in the Neuropterideae ; the form of the seeds, however, 

 indicates that the affinities of the genus lie in a different direction. 



