TEREBELLA FIGULUS. 299 



some previous preparation there, and these are added 

 to the circumference of the orifice of the tube. The 

 under-lip then seems occupied in smoothing the 

 newly-added portion up and down, or possibly cement- 

 ing it to the rest with glutinous matter. 



It seems beyond a doubt that the materials em- 

 ployed in building are first s\vallowed. 



The tentacula of the Terebella figulus seem to vary 

 in number from twenty-five to fifty j they are stouter 

 than those of the preceding species, and, when com- 

 pletely extended, they measure at least nine inches, 

 that is, above twice the length of the body of the 

 animal, so that they are thus capable of sweeping 

 over a very spacious area. Their natural colour is 

 uniformly brown, or tending to carmine ; but when 

 stretching far, they resemble strong whitish horse-hair. 



Nothing is more surprising than the attention of 

 so humble an artist being directed towards such a 

 variety of operations at the same moment. Many 

 tentacula are engaged in searching after the materials 

 many in collecting them whilst others are bearing 

 them towards the edifice ; some are quitting their hold, 

 while others are recovering a load that they have 

 let fall, the architect itself being all the time busily 

 employed in kneading masses in its mouth, disgorging 

 them successively in proper situations, or in polishing 

 the rude workmanship resulting from its labours. 



A perfect tube is half an inch in its external dia- 

 meter, the sides being of considerable thickness, so 

 that it has the appearance of being massive and 

 clumsy ; nevertheless, it is in reality so fragile as to 

 be incapable of sustaining its own weight, on which 



