(45) 

 tecta and the orii:in O"^' the iTiasGnter/ betvvenu the hood aiia the 

 collar, I have come to tho conclusion th.at no vescicle is forraed 

 in tnat species between the two la.yers of the inesentery (i"f two 

 layers exist). The ineseia ery which forms tiie posterior wall 

 of the preoral lobe cavity is found attache a just back of the 

 gan{:lion in the mediaji line aiid there is not ti.e least sit;n of 

 a vescicle other than tiie cavity of tne preoral lobe. ('^it;.24) 



In neiti.er Actinotrocha Gpecies, A., nor Actinotrocha Spe- 

 cies, B. , have I -^ouna a vescicle below tlae gan^.l^on althoUi_^n 

 in both, cases there is a space such as Ikeda (9) has seen, ^ree 

 from mesenchymatous fibers. The anterior boundary o +' this 

 space is rather sharply defined and occasioiially amoni,. loii^-i- 

 tudinal sections a fiber witi; a nucleus is seen runnincj verti- 

 cally from the dorsal to the ventral wall of the hood, .giving 

 the appearaiice of ari aiiterior v/all to the space. These fibers, 

 however, are very much more uelicate than the wall of the collar- 

 lobe septum and v/h at is more, they occur Oi.ly occasionally and 

 are evidently not sections thrcUi_,h a membrane. 



In the Actino tro chae, which I nave examined, there does not 

 exist any vesicle beneath tno nerve t;;a:ii'lion nor any structure 

 which 1 could liken to the heart vesicle of Balanoi^io ssua. 



l^'or the supposed relation of the aorsal blooa vessel to the 

 "subneural sinus":, see Hlood System. 



