700 THE TEREBELLA. 



This is a useful species to the naturalist on account of its plentiful occurrence, and readi- 

 ness to work while in captivity. If a Sabella "be watched while it is building up its 

 curious tube, it will be seen to choose the particles of sand with the greatest care, selecting 

 and seeming to balance them with the tentacles, and cementing each in its place with a 

 glutinous secretion, which has the property of setting while under water. If the creature 

 can be induced to build its case against the side of a glass vessel the possessor has cause 

 to be gratified, for the creature does not waste material, and will often make the glass 

 answer for one side of its tube, thereby permitting the observer to watch its entire 

 economy. 



The skin of these worms is very tough. I remember once having to dissect the 

 digestive organs for a lecture, and losing hour after hour in my endeavours to make a 

 successful preparation. Just as the lecturer's servant came for the dissection, I had begun 

 a fresh subject, and quite lost patience. So I gave the worm an angry tug with the 

 forceps, when the whole skin of one side stripped off, leaving the digestive organs exposed 

 as beautifully as if they had been carefully dissected. 



To give the Sabella a variety of building materials, and to note which it accepts, is 

 always an interesting amusement ; for the worm is very fastidious, not to say capricious, 

 in its choice, and always likes to have a stock of materials from which it may make its 

 selection. 



WHILE wandering along any of our sandy coasts, we frequently come across some 

 moderately large tubes projecting from the sand, and rather conspicuous in the little 

 puddles left by the receding tide. Round their mouth is usually a set of forked filaments 

 which, like the tube itself, are composed of fragments of sand agglutinated together. The 

 substance of this tube is very soft, but very tough, and will endure a tolerably hard pull 

 without breaking. If the inhabitant of these tubes be sought, it will not be found without 

 much labour, for the TEREBELLA. retreats to the further extremity at the least indication of 

 danger ; and as the tube is a foot or more in length, and is always conducted under stones 

 or among rocks, it is not easily dislodged. 



As in the case of the Sabella, this annelid performs its architectural labours by 

 means of its tentacles, which are most wonderfully constructed, so as to be capable of 

 extension or retraction, and at the same time can seize or throw away a particle of sand at 

 any part of the tentacle. The method of working is very well given by Mr. T. Rymer 

 Jones : " If a specimen be dislodged from its tube, it swims by violent contortions in the 

 water, after the manner of various marine annelids ; the tentacular and the branchise are 

 compressed and contracted about the head, like a brush ; and as the animal is very soon 

 exhausted by such unnatural exertions, it soon sinks to the bottom. Should a quantity OA 

 sand be now scattered from above, the tentacular, speedily relaxing, extend themselves in 

 all directions to gather it up, sweeping the vessel quite clean, so that in a very short time 

 not a particle is left behind that is within their reach, the whole having been collected 

 to be employed in the construction of a new artificial dwelling, adapted to shelter the 

 naked body of the architect. 



We will suppose a tube to have been partially constructed into the side of the 

 aquarium, wherein a specimen is about to take up its permanent abode. During the 

 earlier part of the day, the animal is found lurking in its interior, with only the extremi- 

 ties of the tentaculse protruding beyond the orifice, and so it will remain till towards noon. 



But scarcely has the sun passed the meridian, than the creature begins to become 

 restless ; and towards four or five it will be seen to have risen upwards, the tentaculse 

 extending with the approach of evening, until after sunset, when they are in full activity. 

 They are now spread out from the orifice of the tube like so many slender cords each 

 seizes on one or more grains of sand, and drags its burden to the summit of the tube, 

 there to be employed according to the service required. Should any of the tentaculss slip 

 their hold, the same organs are again employed to search eagerly for the lost particle of 

 sand, which is again seized and dragged towards its destination. 



Such operations are protracted during several hours, though so gradually as to be 

 apparently of little effect. Nevertheless, on resuming inspection next morning., i 



