CHAPTER XLVI 



METAXYOID FERNS 



The great bulk of living Ferns may be attached naturalh- by comparison 

 to certain major evolutionary sequences, and may be traced through suc- 

 cessive phases of transition which many allied forms have alike shared. 

 Nevertheless we should be prepared to find also other minor lines of less 

 continuous descent, comprising fewer genera and species. The Metaxyoid 

 Ferns, so called because in their characters they appear related to the genus 

 Metaxya, appear to be such a minor line. This monotypic genus has been 



v'^ 



Fig. 734. Part of a pinna oi Metaxya rostrata Pr., showing the relation of the sori to 

 the veins. ^lore than one sorus may be borne on a single vein. ( x 2.) 



described in Vol. II, Chapter XXXII as one of the Proto-Cyatheaceae, 

 related on the one hand to the Gleicheniaceae, and on the other to the 

 Cyatheaceae, with which family it has in fact been ranked by some of the 

 best authorities. On the other hand, it has certain features reminiscent of 

 Matonia and Dipteris, being in point of fact one of the superficial Simplices : 

 but standing somewhat apart from the rest, it provides a stock open to 

 extension and improvement as the evolution of Ferns pursued its course. 

 The leading features oi Metaxya are the creeping solenostelic rhizome, which 

 bears hairs not scales, and simply pinnate leaves, with a bud attached on 

 the abaxial side of the leaf-base. The broad pinnae have an open pinnate 

 venation, with usually one naked and simple sorus seated on each vein 

 (Fig. 734). But sometimes as many as four sori are borne on a single vein, 

 as seen in a specimen of Metaxya in the British Museum. The sporangia 



