(63) 



from mesencfiymatous cells. He absolutely denies ti.e presence 

 of any iiiesenteried, 



Tiiroui/h the kindness of Mr. Longchamps I have been able to 

 study tlie Actino t rocha o-^ Phoronis vSabatieri and have founa tl:at 

 the iTiesent er-y bet«ee© tire (e*)llar aiua trunk is i; resent althou^jh 

 it id less kighly developed tlian in ctiier species. I am unable, 

 ..iti: ti-.e material at hand, to tjive any opinion as to ti.e i^res- 

 ence of a mesentery between ti.e preoral lu bo and collar cavities. 



Caldwell (3) claims tuat there are but tv/o body cavities ana 

 tiiat these arc separated by a mesentery (coilar-tr-nK mesentery 

 f Masterman) , 



Lon£,champs {12) 3d -"ncxinva -^c./ard the view of Caldv/ell 

 ..biio Ikeda (9) finds the mesentery diviain^ the lube ana collar 

 ..i'lcn, liw.7Cvur, he says, is incomplete. Boti; of ti^.isa investi- 

 j^'ators recoj^ni2;e the presence of the ventral mesentery, 



Menon (17) t-'nas '.nree body cavi ties , (preoral, collar and 

 trunk) a ventral mesentery and indicatioiis of a dorsal mesentery 

 in the trunk, 



MasteriTian (16) considers that the Actinot roc ha have five 

 body cavities. An unpaired lobe cavity, a paired collar cavity 

 and a pairea t-vnik cavity. This idea is based on his study of 

 tne early aevelopment o -^^ tne body cavities aiid not on the adult 

 organization of t'ce Ac tino tro cha, -^'o r in the colla-- ne finds only 



