Above the nervous system separating it from th: 



water system is to be found ths outer perihaemaZ 

 Ti'qts i-i~io opr. 



space. VRe calling the condition of the parihaemal 



A 



system in Stage "E" we eee that the :-nds of the in- 

 terradial projections from the hypogastric and an- 

 terior snterocoeles have grown out over the nervous 

 system spreading in both directions until the out- 

 growths of each interradial pouch meet those of its 

 adjacent fellows in the radii over the origins of 

 the radial nerves; here the ends of the pouches 

 fuse and together they grow out over the radial 

 nerves as the radial perihaemal sinuses. 



In star-fishes where the formation of this per- 

 ihaemal system has been observed, it is said that 

 no fusion tahes place between the diverticulae of 

 the hypogastric and anterior enteroeoele interrad- 

 ial pouches when they meet in the radii, but that a 

 mesentery is formed at the points where the diver- 

 ticulae come in contact. This mesentery is describ- 

 ed as continuing to the :ni of the arm separating 

 the radial spaces into two parallel cavities. 



Nowhffre could I find ouch a mesentery in sect- 

 ions of the larvae of 0.brevispina,nor could I feel 



