SABELLA. 



149 



substances, and which, like the terebella and 

 others, has no organic connexion with the tubes 

 in which their soft bodies are sheltered from 

 danger. The tube that is represented in the 

 engraving is of the natural size, and was drawn, 

 as indeed were most of the figures, from an 

 actual specimen. 



On the same plate as that which is occupied 

 by the terebella, and at fig 5, may be seen a 

 group composed of innumerable tubes, massed 

 together as if they had been a handful of earth- 

 worms compressed into a small space, and then 

 suddenly liberated. These are the tubes of another 

 annelid, called the Sabella, and, like those of the 

 terebella, are built up from the particles of sand 

 on and among which the worm lives. At the 

 bottom of the mass may be seen one of the 

 worms crawling from its tube. These tube-masses 

 may be found in abundance at low water-mark, 

 especially where the corallines are plenty ; and 

 the size of the masses is very various, some being 

 only composed of a few tubes twisted together, 

 while others are several feet in diameter. It is 

 not often that a fragment is found where the 

 tubes are so plainly shown as in the specimen 

 depicted. Generally the surface of the mass some- 

 what resembles a sponge with circular apertures, 



