pearance and position from those in"D" but sine:- they 

 were not figured in the aarlier stage it may be well 

 to refer to then again in connection with Figs. 15. 

 and 16. cb 1,2,3 and 4. The first of most anterior 

 band surrounds the larval organ quite near its tip. 



Near the first band and parallel to it runs the 

 second one also around the larval organ. The third 

 ciliated band is separated from the second by a 

 much wider space than that which separates the 

 • first and second bands. Were it not interrupted 

 on the oral dish, the third ciliated band would 

 lie in the line separating the bivium and trivium; 

 that is, between arms 1 and 2, on the one side and 

 4 and 5 on the other. The fourth band, passing just. 

 posterior to the group of ectodermal elevations ly- 

 ing under the branches of the third radial water 

 tube, surrounds the posterior end of the larva. _ , 

 In "S" the cavities of the oasophagus^have bo- 

 come obliterate! and the two structures appear in 

 section as one solid mass of cells .Fig. 20. st and oe . 

 No degeneration in their size however is to ofesorv- 

 ed and their outer walls remain well defined, the 

 oesophagus retaining its connection with the octo- 



