COEALS FORM AND ACHIEVEMENTS. 



143 



accompanying illustration, Fig. 2 being a portion drawn 

 of its natural size. The colour of the tubes is pinky red, 

 and as the animal that deposits it is bright green, the 

 appearance of a living specimen is singularly beautiful. 



These tubes radiate slightly from each other, though 

 they can scarcely be said to have a common centre. 

 They are supported at intervals by horizontal laminae, 

 through which they pass, so that they bear a resem- 



ORGAN'-PIPE COKAL. 



blance to the arrangement of organ pipes too evident to 

 be unnoticed. 



Now and then they envelop a stone, shell, or other 

 foreign object, and in such cases have a curious way of 

 turning aside for a space, and resuming their original 

 course when they have passed round the obstruction. 

 An example of such a modification is seen on the left 

 'side of Fig. 2. 



In all the species belonging to this group, the polypes, 



