272 T&E BOTANICAL MAGAZINE. LVoi. xxix. No. 346. 



of Undaria, though it remains in the most cases sterile, Undari- 

 opsis may be reduced to a species of Undaria. 



To lay Hirome and Undariopsis under Undaria would seem 

 at a first glance to cover the plants of too different habits. But 

 the three plants have many of chief characters in common. The 

 winged state of ancipitous stem, wanting of mucilaginous lacu- 

 na?, and presence of cryptostomata, characteristic mucilaginous 

 glands and paraphyses capped with mucilaginous mass are more 

 important generic characters, while the pinnate ramification, 

 presence or absence of midrib or fascia, greater or less develop- 

 ment of wing and confluence of sori on both sides of costa are 

 subordinate. The more important generic character is the posi- 

 tion of sorus. With regard to this point, if the three related 

 species had the sorus strictly limited each in a definite area, 

 they would have been laid in different genera. But as Hirome 

 and Undariopsis bear sori, more frequent in the former and 

 though rather rare in the latter, on sporophylls quite resembl- 

 ing to those of Undaria, it seems to me to be unreasonable to 

 lay these two species in different genera. If one compares Un- 

 dariopsis Peterseniana with Undaria pinnatifida he will hesitate 

 to unite the two species in one and the same genus. But on 

 comparing Hirome with Undaria on one hand and Hirome with 

 Undariopsis on the other, there is an evident gradation which 

 will be easily understood from the descriptions given above. 

 From this reason I am to unite the three species in one genus 

 with some extension of the generic characters as the natural 

 consequence. 



Undaria (Suring.) extended. 



Root fibrous, at first distichuously arising ; stem more or 

 less compressed, ancipitous or flattened above, winged, with 

 wings either greatly expanded or remaining narrow, more or 

 less undulato-plicated, and soriferous or sterile ; lamina linear- 

 lanceolate, ovato-rounded or pinnataly lobed, with prominent 

 midrib or thickened into fascia, presenting cryptostomata and 

 dot-like mucilaginous glands ; muciferous lacunae entirely want- 

 ing. Sorus limited on both surfaces of wings forming undulato- 



