(91) 

 gut. This space, hov:ever, in in ^'ree. corrLriunic: atiou wit^"; ulie 

 larval collar cavil:/ (adult rin^ vessel) v/hicj; coutair.s the 

 bloca corpuscles. Under these conaitions the blcoc; corpuscles 

 can pass into the dorsal blood vessel from either end. 



ITasterman (lo) ana r^oule (5^0) both aescribe a vessel on 

 ti;e ventral stomach v:ali of the Actino t ro clia. 1 have not found 

 thiis vessel in the Ac tino t ro ci^.a nor uo I fiiid it in sections 

 Q-^ the critical sta£ie. 



At this time there is but one rin<j; vessel in the suprasep- 

 tal cavity but 1 cOiiSid""" tjn^t it represents both tne receivinj;;; 

 aiio aistri butin.:: vessels of the adult Phoronis. 



Shortly after the critical point in the metaino rphos J s , t he 

 n!esoaer'7ial linin^ on the left side of the oral lirai of the "U" 

 oiiaped alimentary canal be^^ins to sho-.v indie atioiiS of becomiiifj 

 a blood vessel and when the me tairio rpl'osi s is coapletea, a def- 

 inite vessel is seenv/hich opens posteriorly into tne spacious 

 blood sinus arouna the loop of the alimentary caUal. Anteriorly 

 be-f"oro reachinr the traiisverse septum, it divides into tv/o 

 branches which run obliquely upwara ulonj^ the siues o-*^the ali- 

 mentary e3,nal sJmost encirclinf: the same; these finally open 

 into the rinj, vessel o"^ the supraseptal cavity. ( ''^iij,. JO ( a) ) 

 The vessel described becomes the efferent vessel of the adult 

 (Fi£s.7b-77-75-6(.) and its branches become part of the recipient 



