78 ART. 12. K. YENDO. 



shallowly cleft with ribs evanescent in the upper jJortions. Some 

 of the forttis exhibit more divergent characters in the vesicles, 

 being often subfasiform and not homogeneously cylindrical. 

 There are, however, numerous forms which stand between these 

 and the typical forms of Sargassum Horneri. The spathulate 

 leaves are never constant in these specimens but may frequently 

 be found on the typical ones. The branches are approximate 

 or non-approximate, and the texture varies from robust to soft, 

 according to the condition of the j^l^ce where the plant grows. 

 In general, in those which grow in the warmer and more sheltered 

 seas the stems are slender, the interfolial distances longer, and 

 the leaves broader and more deeply cleft. 



In Spec. Sarg. Austr. p. 58, J. Agaedh described another 

 species, viz. Sargassum Fengeri. Judging from the description I 

 am not able to find any legitimate ground for separating it from 

 Sargassum Horneri. 



In Anal. Alg. Cont. III. p. 50, Agardh described still an- 

 other species from a lower portion of a sterile specimen, which had 

 been collected by KjellmaîsT in Jaj)an. The author remarked 

 that the species, i. e. Sargassum 'polyodonium, might be distin- 

 guished from Sargassum Horneri by its having a furrowed cylin- 

 drical stem instead of a triquetrous one. But as I have above 

 stated, the cylindrical but furrowed stem is an im^^ortant character 

 of Sargassum Horneri, especially when yet young. The angulate 

 stem is to be found at the lower portion of the older fronds, 

 and is a result of the falling otf of the basal leaves. I can not 

 find any reason for mentioning Sargassum ]^olyodontum as a 

 distinct species or even as a variety. 



It must be admitted that J. Agakdh's three species have 

 been described from fragmentary or sterile specimens, which as 



