RHABDOPLEURA AND CEPHALODISCUS. 



13 



owes 



uneven, one portion being always more bulky than the rest. The lip of the tube 

 its origin to this local profusion of the secretion. The rings are not necessarily com- 

 plete, indeed half-rings, commencing at the lip and dying out at the other side of 



tr a nonnani, complete colony ( x 3). (Copied from Lankester, 13, plate 37 bis, fig. 2 ) 



d m , the , tubarium ! &, the oldest portion of the colony ; c, bifurcation of a growing branch 



d, completed branches, each terminating in an upright polypide-tube 



