18 ART. 11. — A. IZÜKA : OBSERVATION OX THE 



anterior epitocous region has attained full development. So far 

 as that region is concerned, there is observable no difference 

 whatever from the swarming epitoca (fig. G) either in the pro- 

 portions of dimensions or in the color presented by the sexes. 

 But the worms still drag behind them the degenerated posterior 

 portion which has now become darker in color than before and 

 has somewhat shrunk in thickness. It is usual that more or less 

 of the posterior natural end of this portion is missing, it evidently 

 having become torn off and lost. 



Worms in the state above described are met with a few 

 days — say, for a period of about a week — before the swarming is 

 to be expected. I have found them in greatest abundance in the 

 beginning of October, not only in the natural habitat but also 

 in the aquarium in which only atocous worms had originally 

 been placed. They are known to fishermen under the name of 

 " Hori-bachi " or the " dug-out bachi," so named because the 

 Bachi, found swimming a few days later, are in this period 

 obtained by digging in the mud. 



It seems more than probable that the degenerated posterior 

 portion, now greatly loosened in the consistense of its tissues, becomes 

 more and more torn off at the end, as it is being dragged along 

 by the burrowing worm. And what may remain of of it at the 

 time of swarming, may easily be detached by the first swimming 

 movements. However, it sometimes happens that, among the 

 individuals that have swarmed out, there are seen such as still 

 possess the shrivelled tail-like appendage in varying lengths. 

 Fishermen call these " Ya-bachi " or the " Arrow-Bachi," evi- 

 dently from the remote resemblance they bear to a flying arrow. 



At all events the degenerated posterior portion is destined 

 to be sooner or later completely east off. This leaves an open 



