242 
STRANGE DWELLINGS. 
is yet known, is never found grouped in masses, like many 
allied species. 
The gill-fan of this species is exceedingly beautiful, being ; 
white, dotted profusely with scarlet, and expanding into a i 
graceful feathery coronet. Although the resemblance to the 
serpula is very close, the animal may easily be distinguished ! 
by the absence of the beautiful operculum or stopper, which 
forms so conspicuous a feature in the serpula. 
Perhaps the most plentiful species of this genus is the com- 
mon Sabella ( Sabella alveolar ia ) , which may be found in 
countless myriads on many of our coasts. On several sandy 
shores, especially those of the southern coast, the wanderer by 
the sea may perceive masses of hard, agglutinated sand, pierced 
with innumerable holes. These masses are of great size, and in 
some places are strong enough to bear the pressure of a foot, 
though in others a slight push with the hand is sufficient to 
detach a portion. 
If this perforated sand be closely examined, it will be seen 
to consist of a vast number of tubes, which are fixed together, 
and are further consolidated by sand which has washed over 
them, and lodged between them. When the water covers the 
sand mass, a delicate feathery tuft is seen to protrude from each j 
hole, so that the general aspect is full of beauty. These tufts j 
are the tentacles of the Sabella, and wdien examined with a micro- 
scope of moderate power, each tentacle is seen to be composed 
of a central shaft, with projecting teeth or fringes on both sides. 
There are about eighty of these tentacles, and as they are 
extremely flexible and always in motion, their appearance is 
peculiarly elegant. 
Nothing is easier than to examine the structure of this 
Sabella, though the task of isolating a single tube is not an easy 
one. A penknife will soon break up the tube, and a pair of 
forceps will readily pull out the inhabitant, in spite of the 
arrray of bristles and hooks wherewith it clings to its habita- 
tion. It is but a little creature in point of length, but in point 
of width it nearly fills the diameter of the tube. The ex- 
