. 



RHABDOPLEURA 



601 



This animal forms colonies by gemmation. Each individual 

 consists of a body and a contractile stalk, both of which are 

 enclosed in a horny tube. This tube is supine at first but rises 

 erect later. It is secreted in successive rings by the buccal shield. 

 The tentacles can be protruded through the aperture of the tube, 



FIG. 472. Rhabdopleura Nonnani Allm., 

 individual, from the right side (after Lankester). 

 1, Buccal shield ; 2, feathered tentacles ; 3, region 

 of the "collar pore " ; 4, anus ; 5, trunk ; 6, stalk 

 or pedicle. 



the body being withdrawn again into the tube by means of the stalk. 

 All these tubes are lateral branches of a creeping basal tube which 

 spreads out and branches on the substratum, and appears to be divided 

 into chambers by septa. 



The stalks of the individuals enter this radical tube, and are 

 continued in it as thin strands covered with cuticle, which in travers- 

 ing it perforate the septa. 



The axis of each individual stalk is formed by a strand of tissue 



