248 CHAEACTEES OF TE1BES AND GENERA. 



Illust. Hook, and Bauer. Gen. Fil., t. 42 A ; Moore Ind. 

 Fil., p. 85 B ; J. Sm. Ferns Brit, and For., fig. 133. 



OBS. The general habit of the species of this genus 

 agree in every respect with Cyathea, and are only dis- 

 tinguished by the technical character, which consists in the 

 indusia of Alsophila being either absent, small, scale-like, or 

 forming a nearly complete cup. 



In my Genera of Ferns, 1841, I arranged the species of 

 Alsoplnla under two sections, the first Hymenostegia, including 

 those having a membraneous indusium, very small in some, 

 but in others forming a nearly complete cup, differing from 

 Cyathea only by not completely surrounding the base of the 

 receptacle, there being always an open sinus on the exterior 

 side ; and the second, TricJwstegia, those in which the mem- 

 braneous indusium is entirely absent, the sporangia being 

 more or less covered with articulate hairs. 



Although thirty years have elapsed since that mode of 

 arrangement was published, and having observed much 

 during that period, I find I can make little or no alteration 

 in it, except by amalgamating the genus GymnospJiera, of 

 Blume, with Alsophila, of the species of which I now form 

 a third section, characterised by the sori being destitute of 

 a membrane and of hairs, in that respect not technically 

 distinct, except in the arborescent habit, from Phegopteris, 

 to which it is otherwise related through the genus Lopho- 

 soria. 



In the " Species Filicum " sixty-three species are described, 

 of which about a dozen are marked dubious, the "Synopsis," 

 however, enumerates ninety species including the Appendix. 

 They are widely dispersed over both hemispheres. 



