112 THE TUBIPORA. 



and into which they can retire. So it is with the 

 group represented below. One example is a native 



TUBIPORA, WITH POLYPS ISSUING FROM SOME OF THE TUBES. 



of the Indian seas, the beautiful Tubipora musica, 

 deriving its name from its resembling a cluster of 

 organ pipes in miniature. 



Though the fine red tubes of this zoophyte are 

 compacted together, often closely, and secured by 

 transverse floors or stages, whereon one set of 

 pipes opens above another, the animals inhabiting 

 them appear to be distinct from each other ; that is, 

 they are not vitally united, but merely build up 

 a sort of town, the result of their combined labours, 

 each constructing its own domicile. 



In this case, each polyp is a crimson tube, while 

 the arms are of pure green. When retracted, they 

 are closely folded like the bud of a flower, as the 

 engraving will show, and lodged, as is also apparent, 

 within the folds of a membrane continuous with 

 the margin of the tube. Thus the mechanism is 



