anterior enterocoele together with the tube connect- 

 in- it with the left horn of the hydrocoele are car- 

 ried anteriorly round the oesophagus. Fig.O.ael. and 

 st. In "D" then^we find the stone canal on the right 

 side of a line dividing the larva into symmetrical 

 halves Instead of to the left of the sane line as 

 it is in "C" . Compare Figs.C. and 7. with 9. The 

 anterior enterocoele stops immediately in front of 

 fche stomach and oesophagus. 



From the point v/here the stone cs.nal enter s\he 

 anterior enterocoele the pore canal grows out, passes 



fuse, and an opening breaks through, the water pore. 

 Fig.9. and ll.pc. Thus in this stage the eoelom and 

 hydrocoele are first connected with the exterior. 



In "C" the circular water canal had not closed 

 but existed in the form of a horse-shoe , the concave 

 side of which opened posteriorly; but as the rota- 

 tion of the hydrocoele takes place its horns grow 

 toward each other until they meet. A fusion of their 

 walls then takes place at the point of contact and 

 a complete ring is thus formed. The part of the 

 ring canal, the formation or which hao just been 

 described, lies between radial canals l.and 5. in 



