On Caulerpa anceps, Haiv. 



By 



K. Yendo, RigakusM. 



Dr. Okamura has collected a species of Caulerpa in the province of 

 Boshu and identified it with Caulerpa hracliypits, Harv. The details of 

 the character are well described in the Botanical Magazine.^^ Afterwards he 

 corrected his former determination and referred it to (7. anceps, Harv.^^ 



The original plant of C. brachypus has been first collected by Charles 

 Wright in Japan and described by Harvey ; and C. anceps was knov^n from 

 the Friendly Islands. The principal characters to distinguish them were 

 on the points that C. brachypus has thicker frond with its base and apex 

 obtuse, while C. anceps has thinner frond and the both ends tapering.. 

 These characters, however, are highly variable and seem to have less mor- 

 phological value as Weber van Bosse has already remarked.^^ The last 

 author described a new species with the name of C. Stahlii. It is closely 

 related to C, anceps but separated by having conspicuous serrature and 

 many proliferations. These characters also, in my opinion, seem to be- 

 unfixed. 



The present writer found a small reef in the sea at the Marine 

 Biological Station at Misaki. It is about a fathom below low water mark 

 and covered with the thick vegetation of Caulerpa with exclusive of other 

 plant. ' The first collection on the reef has been made in October, 1898» 

 I identified the plant with C. brachypus. Collections have been repeatedly, 

 made on the ■ same reef at different seasons of the following years leaving 

 always a portion of the vegetation for the future. I noticed that the 

 specimens collected in summer were much more applicable to C. anceps 

 while those in winter, to C. brachypus, 



A doubt occurred to me that if two species might have been growing 

 on the reef. To solve the problem I observed and collected the plant by 

 diving myself in Jan., Apr., July-Aug., Oct., and Dec. No doubt is at 

 present left that the plant assumed the different appearances according to 

 the season. 



1. Botanical Magazine, Tokyo, vol. XIII. 



2. Al^. Japonic^ Exsictge, fasc. I. Ko. 47. 



3. Monog. d. Caulerpes. p. 277. 



