COMMON OBJECTS OF THE SHORE. 315 



three quarters of an inch long, white and opaque, 

 and when seen under a microscope is found to be 

 wrinkled with little rings. And it is wonderful 

 to think of that instinct with which it has been 

 endowed by the Creator, to find a safe dwelling 

 place, constructed for it by an animal altogether 

 so different from itself. 



Not less curious are the little mosaic- work tubes 

 of the Terebellae. Many species of these worms 

 frequent our own shores. Their bodies are very 

 similar to that of the Serpula, and they construct 

 their dwellings by spreading out their tentacula 

 on the sand, till such pieces as they there select 

 are attached to them, and then brought down to 

 the neck. Here the tube commences, " being ar- 

 ranged," as Professor Jones has observed, "with 

 as much regularity as rows of bricks, and cemented 

 together by the tenacious exudation, until a tube 

 is formed encasing the upper part of the creature's 

 body." This tube is sometimes several inches 

 long, and the whole process may be observed by 

 placing the Terebella in a vessel, and putting 

 within its reach the different materials needed for 

 its singular dwelling-place. 



The Terebellaa inhabit the sandy shore between 

 high and low-water-mark, usually quite buried in 

 it to their upper opening, but as the action of the 

 water sometimes raises or depresses the spots in 

 which they are found, they are occasionally seen 

 covered with sand rising some inches above them, 

 and at other times are left quite uncovered. 



The animal while forming its dwelling moves its 

 head continually, from side to side, and it expands 

 its feelers to the length of two inches, when it uses 

 them for digging particles of sand. In summer, if 



