K. OKAMURA.— UNDARIA AND 1 1> SPEi IES. 271 



ped with mucilaginous mass, absence of muciferous lacuna,- and 

 the formation of sori on the median fascia qualify this alga 

 to be laid in a genus other than Laminaria. Based on this 

 ground, Prof. Miyabe and I jointly put this plant very near to 

 Undaria in a new genus Undariopsis 1} in my " Nippon Sorui 

 Meii " p. 128, 1902, and Prof. Yendo quoted that name in 

 the first line of his paper on "Mucil. glands of Undaria." 2 But 

 on getting fully ripened specimens of Hirorne recently, its hav- 

 ing soriferous area on lamina strongly struck me to think of 

 the similarity of having linear sori on the frond of Undariopsis 

 Peterseniana Miyabe and Okam. And considering that many 

 points just enumerated above are common with Hirome and 

 Undaria I came to the conclusion that Undariopsis Peterseniana 

 Miyabe and Okam. is a plant having a very close affinity with 

 Hirome. Now the destitution of a distinct midrib is one of the 

 characters distinguishing Undariopsis from the related genera. 

 But some specimens of Undariopsis have a distinct median fascia 

 in the sterile state or it becomes more distinct when sori are 

 produced, that is when the plant fully matures. As we know 

 Gelidium subcostatum, G. prisioides and G. pinnati£dum have 

 a prominent costa, w-hile it is lacking in many other species of 

 the genus. Again, the five species or forms of Agarum which 

 have costa in various degrees of development have lateh^ been 

 reduced into one and the same species. 3) Thus the insignificance 

 of a midrib is of less importance in referring Undariopsis under 

 Hirome or Undaria. 



In regard to sori, they are always formed on both surfaces 

 of the median fascia in more or less broadly linear or oblong 

 area. But in some specimens, a little expanded upper portion 

 of the wing in continuance with the basal portion of lamina 

 becomes strongly undulato-plicated and bears sori, thus appear- 

 ing like sporophylls of Undaria pinnatifida, and the case is never 

 rare. Taking into consideration together with other characters 

 that the wing of stem is of the same nature as the sporophyll 



1) Diagnosis of the genus not yet published. 



2) Yeneo: Mucilage Glands of Undaria (Ann. of Bot., Vol. XXIII", 11)09) p. 61,* 



3) Setch. and Gardner: Alg. of Northwest. America, 1903, p. 266. 



