122 ART, 12. — K. YENDO. 



Description of the species. The basal portion of the frond 

 is unknown. The stem (possibly of the principal branch) is quad- 

 rangular, ca. 2mm. thick, with longitudinal furrows as in the case of 

 Sargassum Horneri. It is loosely twisted with the lateral branches 

 disposed spirally upwards. The leaves on the stem are thin and 

 membranaceous, pinnatisected, with the general outline linear or 

 linear-lanceolate. The lamina is almost reduced to an elevated, 

 undulating midrib, which becomes a filiform petiole below. The 

 laciniœ are ascending, subulate, narrowly linear, acuminate or 

 shal lowly bi-tridentated at the apices. No cryptostomata are 

 found in our specimen. The leaves on the lateral branches are 

 essentially similar to those on the stem, but are smaller and 

 narrower, with the laciniœ obliquely triangular. The ajDices of 

 the leaves on both parts are pointed or narrowly truncated. 



Vesicles are solitarily disposed near the base of the lateral 

 ramulets. Those found in the lower portions of the frond are 

 spherical, but those in the upper, ovate or elliptical; they are 

 coronated with a pinnatisected leaflet, or sometimes simply mucron- 

 ated ; stipes short and filiform. 



Receptacles are complanated, obovate, ca. o mm. in length, 

 with a cylindrical stalk. They are longitudinally elevated on 

 one surface and shallowly concave on the other, and minutely 

 serrated on the margin. 



Remark on the affinity. The present species is closely related 

 to the next. It may, however, be easily distinguished by the 

 membranaceous texture of the leaves, the extremely narrow lacinise, 

 the solitary receptacles, etc. It has also a strong resemblance to 

 Sargassum filicinum in the vegetative organs, so that the sterile 

 specimens of both plants are almost indistinguisliable from each other. 



Locality. Chikuzen Prov. (M. Yano) (!). 



