GENERAL RESULTS 615 



The question of the classification of the groups of 

 plants with which we have been concerned may be 

 considered here, before going on to the results under 

 each group. To a considerable extent the question 

 turns on the position of the Sphenophyllales ; we have 

 recognised that they form a synthetic group, and have 

 dwelt especially on their apparent relations to the 

 Equisetales and the Lycopods, suggesting the common 

 origin of these phyla. As regards the relation between the 

 Sphenophyllales and the Equisetales there is little room 

 for doubt, as will be shown below (p. 619); this may be 

 expressed by grouping together the two classes under 

 the name Articulatae, in accordance with a suggestion 

 of Professor Lignier's, and adding the new group Pseudo- 

 borniales. The same author regards both Spheno- 

 phyllales and Equisetales as derived from primitive 

 Ferns, 1 and although I am not able to follow all his 

 arguments in detail, I think there is some evidence of 

 affinity in this direction. The Sphenophylls resemble 

 certain Ferns in the venation and frequent dichotomous 

 division of their leaves ; they are not really micro- 

 phyllous like the Lycopods. The oldest Equisetales 

 likewise had forked leaves, while in the Devonian 

 Pseudoborniales, which clearly belonged to the Articu- 

 latae, the leaves were highly compound. So far as 

 the leaf-characters are concerned, the Lycopods appear 

 to stand alone as the one truly microphyllous phylum. 

 On the other hand, the Sphenophylls certainly approach 

 the Lycopods in their anatomy, though the taxonomic 



1 O. Lignier, "Equisetales et Sphenophyllales, leur origine filici- 

 neenne commune," Bull. Soc. Linn, de Normandie, 5 6 ser. 7 e vol. p. 93, 

 Caen, 1903; " Sur l'origine des Sphenophyllees," Bull. Soc. Bot. de 

 France, six. 4, tome viii. p. 278, 1908. 



