68 DEVELOPMENT OE THE STAEEISH 80LASTEE ENDECA. 



PLATE IV. (cont). 



rectal caeca are cut through. The surface prominences are due chiefly to 

 spines, those which form the denticles being particularly large. The 

 epigastric and hypogastric mesenteries sepai'ate the epigastric and pharyn- 

 geal coeloms respectively from the hypogastric ccelom. A Tiedemann's 

 body is closely attached to the ring-canal of the hydrocoele. The other 

 parts of the hydrocoele in section are the ampullae of the tube-feet. 



