29.2 THE AQUARIAN NATURALIST. 



Although these organs when contracted are col- 

 lected into a brush scarcely double the thickness of 

 the animal's body, so enormous is their extensibility, 

 that they can be stretched out to the length of four 

 inches,, or half the length of the body, thus sweeping 

 the area of a circle eight inches in diameter. 



A thin internal coating, resembling silk, lines the 

 whole tube, and at the same time serves as a real 

 cement to unite and strengthen its innumerable parts. 

 This silk -like material is derived from a glutinous 

 slime which exudes from the surface of the body of 

 the Terebella. 



Notwithstanding the unrivalled expertness and ex- 

 pedition with which this Annelid an advances its work, 

 it has never been observed to resume possession of its 

 tube when once forsaken. To obtain the shelter of a 

 new dwelling in place of the old, its labours are 

 invariably recommenced from the foundation. 



Observation does not seem to have supported any 

 conjectures relative to the food of the Terebellee. All 

 of them appear to reject animal substances, so that 

 perhaps, like other genera, they may derive their sub- 

 sistence from swallowing sandy or earthy matter, 

 mixed up with organized particles. The timidity of 

 these worms would appear to prevent the possibility 



hollow interior; by this movement a cup-shaped cavity is 

 formed, in which the object is securely held by atmospheric 

 pressure; this power is, however, immediately aided by the 

 contraction of the circular muscular fibres. Such, then, are 

 the marvellous instruments by which these peaceful worms 

 construct their habitation, and probably sweep their vicinity 

 for food. 



