(65) 

 i:.ecome separated ar^ci apply themselves hern aijci tliCre to the \7alls 

 of ti.e preoral lobe. The mesentery reniains intact ana canuot 

 be coiiSiderea as a secondary structure as nas been sUi^-ested by 

 Loncchamps. Mthou^^h 1 at:ree \viti> Ikeda'o statement tnat tne 

 mesentery between the lobe aiici the collar is i.icompleto laterally 

 in tre fully developed Actinotrocha, yet in ti-.e Actinotrocna of 

 Phoronis architecta, at least, it must be cor^sidered as a de-^i- 

 liite mesenter-y. 



The fully formed Acti nc t rochae (Species, A. ana Species,B.) 

 do not sho',v a complete epitnelial linin^^ to the preoral lobe but 

 the mesoaerm cells are arran^^ed as I have described in tiie younj., 

 larva. 



It is statea above in the part on tl:e mesoderm tl;at I do 

 not find tt^at the lining; of tt-^e collar cavity is o+' enterocoe- 

 lic orii,:in in Phoronis architecta. However, in tne fully 

 forme 0. Actino t ro cVia there is an undoubted mesodermic epithelium 

 lininr the somatic '.vail. This layer is very conspicuous imme- 

 diately be^^ore metamorphosis because it becomes separated from 

 ti;e somatic wall prior to becomint^ transfcrmea into tne ri tit. ves- 

 sel of ti.p ,.ault. (■Pitrs.51(t:)-51(>i) ) 



The splanchnic wall of the collar cavity in t iic Ac tino t roci:- 

 ae that I have examined is devoid of a mescderirial linin^,^ and the 

 occurrence of me",soderr;i cells on t>ie wall is verj infrequent. 



