(b6) 



,etv,-..B the larval ue.hriala .na U.e .eph. : dl a f tae aault . 

 While his>i^. 64 e shors the .arval i.ephridia. camls, hi. T^ig. 

 66, which is a cross section ti'iro^-yy.h the anterior end of a youn^, 

 Phoronis and which shows a section through the youn,. uophridinm 

 of the ;^ault, does not convince me that he is aealiUi, with the 

 same structure, 



V as c 111 ci.r S y s t exrr.j-^ It rill be remembered that the vascular 

 system of the full;' aeveloppu Actinctrocha Species, A. consistea 

 of a dorsal blooft vessel ('F'igs. 5„( ^ ) - (j^) - (h) ) running alon^j the 

 mediaii lin-^^ of the stomacli from the aorsal insertion o^ tir:e mes- 

 entery between tne collar and tmnk to the posterior end of the 

 stomach, its lumerj beini, a part of the sei^mcntaticn cavity; a 

 bunch of blooa caeca fo nrxe d at tlie posterior end of the storaach 

 as evaginationso f its splanchnic me so dermal covering; a loose sac 

 of mesodermal tissues arisiing on the somatic ./all of t):o collar 

 segmeut and enclosing the larval collar cavity. (Figs. 50-51 ( f) - (g-)- 

 (h) ) (See section on the /re tajTiorpho si s , ^or aiscussion of 

 ii.e "post-oral rin,., sinus", ventral vessel ana the "ring s-in";^" 

 at til- junction of the stomacn and intestine) 



There are several important points in the vascular systezn o !^ 

 tne Actinctrocha v.'-hich must be taken into account in oraer to 

 understand its metairiorphosi s into the vaac\>lar system of the 

 young Phoronis. "Pirgt, that the dorsal blood vessel, which is 



