240 
STRANGE DWELLINGS . 
formed, in which the object is securely held by atmospheric 
pressure ; this power is, however, immediately aided by the con- 
traction of the circular muscular fibres. Such, then, are the 
marvellous instruments by which these peaceful worms construct 
their habitations, and probably sweep their vicinity for food.’ 
It is a remarkable fact that the Terebella does not form tubes 
during the early portions of its life, but swims about freely, like 
the nereis and other marine annelids. It has a head, eyes, feet, 
and antennae, and roams about at will ; whereas, in its perfect 
state, it has neither head, nor eyes, nor antennae, nor true feet, 
the last-mentioned organs being modified into the tufts of hooks, 
and bristles, by means of which it moves up and down its tube. 
The reader may perhaps remember that the barnacles and many 
other stationary marine animals are free during their prelimi- 
nary epochs, and only become fixed when they attain the perfect 
form. To our minds, the former seems the more perfect, and 
certainly the more agreeable state of existence; but we cannot 
measure the feelings of such an animal by our own, and maybe 
sure that the creature enjoys existence as much while shut up 
in a tube, as when roaming the ocean at liberty. 
Another species, Terebella figulus , sometimes called the 
Potter, prefers mud as the material for its dwelling, and con- j 
trives to make the dark sea-mud so adhesive that it is capable 
of being formed into a tube. 
As may be easily imagined, this tube is extremely fragile, and 
cannot be removed entire from the water without the exercise ; 
of much care, its own weight being mostly sufficient to tear it 
asunder. The walls of the tube are tolerably thick, and the tube 
itself is of some size, measuring nearly half an inch across, and 
is always found to be protected by the earth upon which it is 
placed. It is a rather curious fact that the tentacles of this 
species are of extraordinary length', extending for some eight or 
nine inches beyond the entrance of the tube, the animal itself 
measuring little more than four inches in length. 
The last species of Terebella that will be mentioned, is a very 
