372 MOSSES AND FERNS chap. 



mentosa, both of limited range, and confined to the Malayan 

 region, The affinities of Matonia are probably with the 

 Gleicheniaceae, rather than with the Cyatheaceae, with which 

 they were formerly associated. The large flabellate leaves of 

 M. pectinata are much like those of some species of Gleichenia, 

 and the arrangement of the sori is much the same. There is, 

 however, a conspicuous umbrella-shaped indusium of firm tex- 

 ture, and in their form and dehiscence the sporangia are more 

 like those of the Cyatheacese. The development of the spo- 

 rangium, according to Bower (19), is much like that of 

 Gleichenia. 



The structure of the stem in Matonia pectinata (Seward 

 (2) ) is very much like that of Gleichenia pectinata, but there is 

 a second and sometimes a third cylindrical stele within the 

 primary stele (Fig. 213, D). 



Zeiller (i) from a comparison of Matonia with the fossil 

 genus Laccopteris, which occurs in early Jurassic beds, con- 

 cludes that the two genera are very closely related, if not actu- 

 ally identical, and represent the earliest forms of the Cyathe- 

 ace^, and that Matonia is the last remnant of a family now in 

 process of extinction. 



The Hymenophyllace^ 



The Hymenophyllacege have been the subject of much dis- 

 cussion on account of the assumption made by all the earlier 

 writers that they were the most primitive of the Pteridophytes. 

 This was based very largely upon the apparent resemblance 

 between the delicate sporophyte of many of them and the leafy 

 gametophore of the Mosses. More recent study of their de- 

 velopment, especially the gametophyte, has led to a modification 

 of this view, althous:!! it is still held bv manv botanists. It 

 seems more probable that the peculiarities of both gametophyte 

 and sporophyte are due to the peculiar environment of these 

 plants, which grow only in very moist places, indeed are almost 

 aquatic at times. They are for the most part extremely deli- 

 cate Ferns of small size, and with few exceptions are tropical. 

 Many are epiphytes, and these have the roots very poorly de- 

 veloped or even entirely wanting. The leaves are, with few 

 exceptions, reduced to a single layer of cells, except the veins, 

 which gives them a striking resemblance in texture to the leaves 



