July, M17.] k. YENDO:— NOTES OX ALGAE NEW TO JAPAN. VII. 189 



of frond unexamined. Hence the present determination is 

 provisional. 



The specimen distributed as No. 15 Ph}'c. Bor.-Atner. under 

 M. Grevillei Wittr. has a close resemblance to the present, 

 eventually to M. cylindraceum Kjellm. While yet very j^oung, 

 the fronds of M. Grevillei, M. Yahlii and M. cylindraceum art 

 ver\- much alike in aspect. But in the typical form of M. 

 Grevillei, frond splits downwards into many linear segments, 

 almost to the base. In the other two, the apical part of 

 frond is ruptured with several, broad lobes but rarely till to 

 the base. 



Rosenvenge extended the specific limitation of M. Grevillei 

 as to comprise M. Yahlii J. Ag., M. arctica Wittr., M. sac- 

 codeum Kjellm., M. cylindraceum Kjellm., M. angicavum 

 Kjellm., etc., under its formae. He might have been quite 

 right to do so. But we can not accept his arrangement be- 

 fore we have rearranged all the species of Monostroma as to 

 keep uniformity of the specific limitations. I choose at present 

 to mention M. Yahlii J. Ag. as an independent species, reciting 

 here what Collins' ; has ever spoken of Rosenvenge's view : — 

 " In forms so closely related and passing into each other so 

 much as do the forms of Monostroma, it is more a matter of 

 personal preference or of convenience than anything else, 

 whether the forms are distinguished as marked varieties or 

 nearly allied species." 



Locality. Otaru Bay(!); Kitami Prov.(!); Northern Kuriles(!). 



Distribution. Greenland to Massachusetts; Alaska. 



Bryopsis corymbosa J. Ag. 



Alg. Med., ]). 21.— Id.: Till Alg. System. VIII, p. 27 — De 

 Tom : Syll. Alg. I, p. 433. 



(For other references, see: De Toni, I.e.). 



The plant is found in caespitose tufts of 1-2 em in height, 

 with slender and flaccid frond, resembling Chlorodesmis coinos/i 



]) The Qlvaceae of North America, )>. IS. 



