(74) 



1 nave been urjable to find the "rii.;^ sinus" valiich, accora- 

 inj: tc Masteririan, connects tne aorsal veasel witn the ventral 

 vessel at Zh<^- euOi of the stoniach, iio r have 1 seen ti:e "postoral 

 rin^: sinus" conijectinj^ the aorsal vessel with t):e veritral vessel. 



1 shall discnss Mas t e rrnan ' s "post-oral rin^: sinus", "ven- 

 tral blooa vessel" ana "rin^, sinus" (siti'atea at the junction 

 tet-.v^^n the stomach ana intestine) in the section on the metamor- 

 phosis, 



Th-re is unaoubtedl- a space betv/een ti:e wall of th.e peri- 

 anal ring and its mesodermal liniui,, (Fig. 49) in preservna spec- 

 imens v.nich 1 suppose is wnat Ivlaster.aan calls the "n.*Pi:io.l rin;-," 

 but it aces not become any organ of the aault. 



As otatea above, 1 believe v/ith Wilson, Caldv/ell aiid Ikeda 

 that tiie ca.vi!ty of the collar and its somatic ineBodermal lining 

 I -^ CO me thp- rin^^ vessel of the adult. 



I shall continue the discussion o -f" the furtner development 

 -f" the dorsal blood vessel into the efferent ana afferent veooels 

 ■•■ the adult in the section on the metam.orpiiosis. 



Mastenxian speaks of haemal sinuses passint, dovm the tenta- 

 cles but says that they are not very aeciaea. Ikeaa nas ,ho 'vevejj- 

 investigatea these structures carefully ana I thorou:^yiily agree 

 v'ith his view that the cavity of the collar together v/ithi its 

 somatic lining extends into the tentacles anai tiliat these proloag- 



