(104) 



tentacular v^^ysels opeu into tne outer or recitieut vessel but 

 at one end the tentacular vessels o?en into tr.e irmer or distrib- 

 uting; vessel. Thid section, together \n th sections anterior 

 and posterior to it, sLov.- coi.'cliia ivoly tliat the te..tacular vessel 

 has two separate openings, one into the distributing vessel, the 

 other iLto the recipient vessel and that the distributing and 

 recipient vessels are completely separate. A longi tuainal sec- 

 tion tn'-ou^^h the anterior end of Phoronis architecta shov/s con- 

 clusively that the tentacular vessel divides into tv;o branches, 

 one opeiiiii^ iiito the recipient vessel and the cths'^, into tliC 

 distributing^ vessel. 



A little iTiO re posteriorly, the rint;-liKe dist ri butinj; ves- 

 sel opens into a median lon£;ituainal vessel I'yin^ between the 

 Gesopha*_^us aiid r^ectum but close to the \7all of tlie fo'~mer, ('Pi.js, 

 67-6L) This vessel, whicii is tr.c afferent vessel, pierces the 

 transversa yeptum ("Pi,j;.69) ana rnxin posteriori:,' (within t]-:e rec- 

 tal or posterior chasJjer) betv/een the tro iirma ■*" the alimentary 

 canal. At the point \'{lr ere the vessel passes throuj,]; the septum, 

 mere is a thick layer of muscle ^ibers surrounding the -^onner 

 v:hich undoubtedly has tne power of shutting, off the blood supply 

 to r, Kf? tentacles axio -mich nia.7 be very necessary tp prevent the 

 animal fro 1:1 deeding, to death v/hen the lophopnoral crovm is cast 

 away. C^igs.ee to 71) 



