350 ASAJIRÖ OKA ; ON THE SO-CALLED 



matic nature are, it appears to me, of great service. 



Figs. 2-8, Pis. XXXIV-XXXV, represent cross sections of the 

 ciliated tubes with the neighbouring parts of the polypidal body. 

 Beginning with the lowest of the series, we find in fig. 2 that the tubes 

 communicate laterally witl> the c;ivity of the 8rd tentacle (counted from 

 the median line, the median tentacle being No. 0), together with which 

 it opens into the lophophoral cavity. In fig. 3, the tubes are already 

 closed, but their wall is not of equal thickness everywhere, the part fur- 

 ther removed from the median line of the animal being nearly as thin 

 as the lining epithelium of the body- cavity. The inequality in the 

 thickness of the wall disappears in the few following sections, not figured 

 here, in which the lateral jjortion is just as thick as the median. In 

 the next figure (fig. 4) the lumina of the 2nd tentacles of both sides, 

 which open below into the cavity of the ciliated tubes, are seen .-dready 

 separated from the latter. It is one of the places where the cavity of 

 the second tentacle opens into that of the tubes that CoRi figures and 

 describes under the name of " Nebentrichter." In the same figure, we 

 find that the two tubes have their median walls already in contact, 

 and in fig. 5 they are united into a single tube, with the lumina of the 

 second tentacles on both sides. This single tube stands, further, in 

 communication with exterior by means of a small pore (p.). The 

 next figure (fig. 6) represents the tube on the point of being divided 

 ao-ain into three small tubes, which are nothing other than the lining 

 epithelium of the tentacular luminn, as may be seen from figs. 7 and 

 8. The only ditference between these and the lining membrane of other 

 tentacles is that the former have decidely more nuclei in a section than 

 the latter. Thus in the individual represented l)y this series of sections, 

 the ciliated tubes (which hardly deserve this name on account of their 

 shortness) are continuous with three median tentacles at the upper end, 

 and a little below and laterally with the tentacles No. 2, by meiins of 



