IK) 



I. IKEDA. 



a species of Phoronis which was quite unknown to me before. On 

 visiting at once the spot where it was obtained and which was only 

 about four feet deep at a distance of a few minutes' rowing from th 

 Laboratory, we have found the very Actinian, a Gerianthus, which was 

 before supposed to have been captured, but which in fact remained 

 behind, having been divested of only its gelatinous tube together with 

 the Phoronis inhabiting it. The latter, being similarly colored as the 

 tentacles of the Ceri (infinis, might easily be mistaken for these. 



About a month later, after I have left the Laboratory, Kuma, the 

 collector, reported that the same Phoronis turned cut to be something 

 very common, almost every individual of the Gerianthus being found 

 in company with a more or less large colony of it. 



During July in the following year (1902), I have had opportunities of 

 verifying the truth of Kctma's report and of myself observing the Phoronis 

 in its native habitat. 



In the inlet of Moroiso, at the mouth of which is situated the Misaki 

 Marine Laboratory, as well as in that of Koajiro, next north to the 

 one just mentioned, the Gerianthus — a large species with deep reddish 

 blown tentacles — inhabits the shallow muddy bottom at places in such 

 abundance that one can not help treading upon it with every step. The 

 gelatinous tube, in which it lives, may be as thick as one's arm. Ex- 

 cepting the smaller tubes, almost every one may be said to be tenanted 

 by the Phoronis, as was reported by Kuma. At low tides the bottom is 

 nearly exposed or is covered by only a few inches of water. The Gerian- 

 thus is then invariably retracted deep into the tube, but the upper end 

 of this remains visible above the mud surface, together with the Phoro- 

 nis colony, which radiates forth from the tuba-opening simulating in a 

 way the appearance of the expanded Gerianthus tentacles. Moreover, as 

 before indicated, the Phoronis is of the same color as these ; so that, we 

 sesm to have here a case of mimicry in which the helpless Phoronis not 

 unlikely benefits itself, in an indirect way, of the protective influence of 

 the nestle-organs possessed by the host, which at other times of the day 

 will be found expanded at the identical spot. It is difficult to say if 



