(93) 

 vessel but such is not the case in the completely raetarro rfhosea 

 Ac tirio tro cha., 



'From a corripa.risor. of Llastennai:' s description of the vascu- 

 lar systeiri of the Actinotrocha and Ikeda's and my own descrip- 

 tion 0.^ the same be-f'ore ajia after metamorphosis, it is seen at 

 once that this systea develops more precociously in the form 

 that Kastermaii studied. This conaition, togetiier with the 

 facts that the lumen of the blooa vessels are parts of spaces 

 between the Y/all of thp -^vt and its mesodenrial liixiiii^ and that 

 the mesodemal linin;- of the alimentary caiial fits loosely viiile 

 the blood system is developing, gives additional \vei(-ht to J/Tas- 

 ternan's statement that the dorsal vessel opens into the so- 

 colled "suoneural sinus". Kov/ever, in the Actino trochae that 

 I i-ave exarfiinea such a connection does not exist and, as stated 

 above, a "sufcneural sinus" or cavity caused by a lacK of conti- 

 guity betv/een the mesodermal wall of the preoral lobe ana tnat 

 of the collar cavity is not present. 



