JOURNAL OF THE COLLEGE OF SCIENCE, TOKYO IMFEEIAL UNIVERSITY. 

 VOL, XLIII., ARTICLE 1, 



A Monograph of the Genus Alaria. 



By 



Kichisaburo YENDO, Rîgahuhakushi, 

 Professor of Marine Botany, The HoH-aido Imperial Unirersify, Sapj)oro. 



With 19 plates and 2 texffigures. 



" Bei wenigen Gattungen unter den grosseren 

 Meerespflanzen sind die Ansicliten der Autoren 

 über die Zahl der Arten so abweichend, v.-ie bei 

 Phasganon." — ErpEECHT. 



More than 32 species of Alaria have been described by varions 

 writers since Geeville established the genus in 1830. Not a few 

 of them have been reduced to synonymous positions of the others 

 and only about half of them are now admitted to be more or less 

 valid. But the synonymizations by different writers frequently do 

 not agree with one another so that the true number of valid 

 species is not yet satisfactorily fixed. The complaint made by 

 EuPEEGHT seventy years ago may still be repeated by modern 

 algologists. 



The ambiguity of the specific limitation of Alaria is un- 

 doubtedly due to the following facts ; first, in most species the 

 stages of development as w^ell as the habit of the plant are not 

 observed by the describer himself, thus different forms of one and 

 the same species due to the ages or conditions of the habitats 

 may often have been mentioned in separate and independent 



