170 BOTANICAL MAGAZINE. [Voi. xvii. 



Hedopliyllum we find a remarkable parallelism between Hedophyllum, 

 Thalassiophylhtm and ArihrotJiam,m{s in the mode of branching. 



The normal branching of Thcdassiopliylltcm is a simple bifm-cation. 

 The lateral branches, which sometimes occm- in a considerable number and 

 size, are irregular ones, as has been already remarked by Eosenthal and 

 Setchell.^^ The both arms are the scrolls of perfoi^ted laminae constantly 

 unrolling and growing upward. •••' The old portion of the lamina sucessively 

 wears away leaving spiral scar around the stem. It goes on infinitely. 

 The circumstance is similar in Hedopliyllum spiral e ; the only difference 

 lying essentially on the wanting of the foramens and the Hmitted number 

 of rolling. Compare fig. 7 and S. 



In Arthrotliamniis the case is httle modified. The turning of the scroll 

 is in the majority restricted to only once. Prof. Miyabe of Sapporo reports"^ 

 that the stems of Artlirotliamnus Kurilensis sometimes turn twice. But 

 in the stems of Arthrothominits hifidAis it is exclu"-:ively only once as far 

 as I could actually observe. If we trace the outermost branches, from 

 the primary stem upward, we shall find that the terminal lamina has been 

 revolved as many times as the repetition of the dichotomy. It rolls in- 

 finitely as it were. (fig. 9.) 



The secondary laminae of Thalassiophylhim and Hedopliyllum spirale 

 are unsymmetrical, while the adult blades of Arthrotliamniis are the contrary. 

 But the young stage of the secondary laminae of the latter species, as has 

 been above remarked, ft an unsymmetrical blade. This must not be over- 

 looked in the phylogenetic speculation. 



Setchell enumerated Ci/matliere, Costaria, Agarum, Tlialassiopliyllum 

 and Artlirotliamnus under the subtribe Agariae in the tribe Laminariideae. 

 .And Undaria (Ulopterix), Ecldonia and Eisenia under the subtribe of 



1. Kosenthal : Flora. 1890. p. 140. 



SetcKell and Gardner : Algae of N. W. Araer. p. 267. 

 * About the mode of formation of the lateral branches the present writer can not hold 

 in the opinions of Kosenthal and Setchell. The former reported that the lateral branches 

 are originated at the wounded margins of young foramens, and Setchell seconded this view. 

 If^this be the case always the branches must be often found on the lamina, because the 

 young foramens shall take their places on the lamina as the scroll unrolled. But the lateral 

 branches are always found arisen on the stem without direct continuation with the spiral 

 scar. This can hardly be explained by their view. Tlie present writer found young stages of 

 the branches on a pretty old part of a stem, without any relation with the lamina. Anyhow 

 the lateral branches are not normal ones, but of secondary nature. 



2. Miyabe. Laminareaceae, in Reports of the Fisheries of Hokkaido. III. p. 49. 



