194 TEREBELLA. 



many of which lead to fallacies. I do not deny, by any means, that 

 there may be some fixed members, and some fixed forms. But in ex- 

 amples innumerable, so many, that in fact I fear to refer to them, many 

 such details are absolutely equivocal. Some things, such as dimensions 

 and proportions, which we reasonably deem very essential, are unfortu- 

 nately no less so. I am far from disparaging the labours of such learned 

 naturalists as have followed the preceding course, but I cannot suppress 

 my opinion, that if persons so skilful devoted their care to perfect living 

 specimens, instead of to those chiefly dead or disfigured, they would have 

 found far more prominent, more permanent and satisfactory features, 

 whereon to found their systematic arrangements. 



Undoubtedly the number of the tentacula in the Terebella figulus is 

 dependent on age, or it may denote differences not yet sufficiently re- 

 cognised. None, except the fine specimen represented, have had above 

 twenty-five. But in this individual that number was doubled. Those 

 of this specimen seem to be all different dimensions ; observing, however, 

 that the aspect of such variable organs is wonderfully modified. They are 

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

 pletely they reach nine inches, that is above twice the length of the body 

 of the animal, being thus capable of sweeping a spacious area. Their 

 natural colour is uniformly brown, or tending to carmine, often shewing 

 dark tips. When stretching far, they resemble a strong whitish horse 

 hair. 



In fabricating its dwelling, this creature gives an evident preference 

 to mud, as the most suitable of materials. Should a quantity of this 

 substance, of sand, and of comminuted shells be alike accessible, the first 

 is always preferred, and the last always rejected, or reluctantly used. 

 The Terebella is continually in quest of materials. The contents of a 

 watch-glass introduced within its reach at night, have generally disap- 

 peared against morning. 



If the animal be dislodged from its tube, the body becomes closely 

 coiled up, but the tentacula speedily search around, sweeping up every 

 thing within their reach ; and if the materials are abundant, a covering is 

 speedily formed. It contracts greatly while the earlier part of the edifice 



