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, benig 

 white, dotted profusely with scarlet, and expanding into a 

 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 alveolarid), 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 

 hole, so that the general aspect is full of beauty. These tufts 

 are the tentacles of the Sabella, and when 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 

 array 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- 



