400 HOMES WITHOUT HANDS. 



Theee is another marine annelid which constructs calcareous 

 tubes, and which is sufficiently interesting to warrant a short 

 notice. If the reader should happen to have in his possession a 

 piece of stone, or an oyster-shell, that has been for some time 

 immersed in the sea, or if he has a piece of the large tangl6>- 

 weed that is so popular as a barometer, he will see that upon the 

 surface are certain tiny calcareous tubes, scarcely thicker than 

 hairs, and rolled spirally so as to form flat circular objects, about 

 as large as pins' heads. They are firmly fixed to the objects on 

 which they are placed, and are often thought to be the earlier 

 forms of the serpula. 



These, however, are distinct animals, called Spirorbis by 

 naturalists, who have noticed that their spiral tubes bear a great 

 resemblance to the planorbis shell, which is so plentiful in our 

 rivers and ponds. A tolerably powerful magnifying-glass is 

 needed before the real nature of the Spirorbis can be made out ; 

 but a short examination wiU show that not only is the little 

 worm furnished with gills or branchiae which closely resemble 

 those organs in the serpula, but that, like that animal, it can 

 shut up its tube with an operculum of a conical shape. 



Another example of a submarine builder may be found in 

 the well-known Teeebella of our coasts, sometimes known by 

 the name of Shell-bindee. Sandy shoals are the best spots for 

 the TerebeUa, and in many places there is scarcely a square yard 

 of sand without its inhabitants. Like the serpula, the TerebeUa 

 constructs tubes, but, unlike that animal, it makes the tubes of a 

 soft and flexible texture, although the materials which it em- 

 ploys are far harder than those which are used by the serpula. 

 The TerebeUa has the art of making its submarine tubes of 

 sand, which it agglutinates together with such wonderful power, 

 that if Michael Scott's impish famUiar had only been acquainted 

 with natural history, he might soon have learned the art of 

 making ropes of seasand, and have turned the tables on his 

 master. 



Should any of my readers be desirous of finding the habitation 

 of a TerebeUa, he may easily do so by repairing to the nearest 

 sandy shore, and looking under every large stone or piece of 

 rock. There he wUl probably find some loose tufts of sandy 

 threads, which are fixed to the mouth of a flexible tube, made 



