i 



Fig. I. — A portion of the branching tubular growth formed by Rhabdopleura Normani, fixed to 

 and spreading over the smooth surface of an Ascidian, dredged at Lervik and drawn of 

 three times the natural dimensions. The colourless tubes (b) stand up freely from the surface 

 to which the rest of the growth is adherent, and from each of them issues in life (as seen at 

 bb) a polyp such as that shown in Fig. 2. Each polyp is continuous with the dark internal 

 cord (or rod) which is seen traversing the whole of the tubular system, a, points to the 

 main and oldest portion of the branching stem ; c, points to a " leading" shoot which is still 

 adherent and will give rise to young buds right and left which will form upright tubes like b. 

 The inset d represents a piece of the tube magnified so as to show the rings by which it is 

 built up. 



