102 BOTANICAL 3IAGAZINE. [Voi. xvii, 



In the course of study of some Laoninaria of Japan. Dr. Okamura 

 has noticed the " dark dots " in the fronds of Laminaria Fetersem'mia, 

 Kjelhu. and figured them in his paper " On Larainaria of Japan.^ He 

 remarked at the same time that these spots are characteristic to the 

 species and might be served to determine it. These ^^ dots " were known 

 afterwards by Prof. Miyabe to be also present in Undaria pinnaHflda, 

 The similar " dots/' in structure and in position, are abundantly found in 

 our plant. To secure the exact knowledge on the function and properties 

 of the spots a further study is wanted. The brown content, apparently 

 alike the content of the /'dark" cells, is always found filling up the 

 subepidermal cells of the rib, stipe, sporophyll and holdfast. Ifc is especially 

 rich in the cells at the marginal portion of the sporophyll. 

 RELATION TO OTHER SPECIES. 



There is a little doubt left that the plant in question is closely related 

 to Vndaria jrinnatifida (Harv.) Sur. Both sporangia and paraphyses are 

 similar in every respect in the two plants. It difters from it by having 

 no ligule at the transition point and by the shortness of the stipe. The 

 typical plant of the present species has the insignificant pinnules ; but 

 some of the extreme forms are often furnished with more or less regularly 

 pinnated segments, which suggest the aberrant form of Undaria pmnatifida. 



No parallel character has ever been noted about the transition region 

 expanding downward. This depends, no doubt, to the thin margin of the 

 ancipitate stipe. The writer is inclined to think that the similar pheno- 

 menon might occur in other plants, especially in Alaria, and consequently 

 the shape of the base of lamina might undergo gradual change according!; 

 to the age of the plant. 



The essential character of the plant to establish a new genus lies on 

 the sori at the costal area. The sporophyll is often wanting in our plant, 

 but the sori in the lamina are constantly found as soon as the plant had 

 attained to its maturity. If the both are present they are free from one 

 another. The case is just contrarj^in Undaria pinnatifida : the sporophyll 

 being the principal soriferous area, only in the aberrant forms the area 

 running continuously into the lamina. 



Our plant would stand closer by Undaria pinnatifida than Pleurophjcus 

 Gardini, Setch. et Saund. stands by Larainaria Peferseniana, Kjellm. 

 and Laminaria radicosa, Kjellm. But to enumerate the plant under the 

 genus Undaria would make it cover the plants which are too widely 

 diverged in their character. 



1) Botanical Magazine, Tokyo. Vol. X. P. 98, 



