TEREBELLA. 187 



mon to the tenants of the deep, whose faculties are most energetic, and 

 their industry most active, while the upper world are buried in sleep. 



Comparing the effects of this persevering artificer with manual 

 powers, even when these are aided by the high prerogative of reason, it 

 will be understood how the operations of sixty, eighty, or a hundred 

 prehensile organs, all directed towards the same purpose, can produce 

 definite and considerable consequences. 



At first sight the numerous tentacula seem only so many long, 

 slender, cylindrical, fleshy threads, of infinite flexibility. Looking to 

 them more attentively, we see that in exercising any special function, 

 the portion which is applied to the surface of objects, flattens into twice or 

 thrice its ordinary diameter, and Avhile conveying the sandy materials 

 to the tube, these are seized and retained by what appears a slit in each. 

 Thus the tentaculum becomes a flat narrow ribband, folding longitudi- 

 nally in different places to hold the particles securely. 



Although those organs collecting as a brush be scarcely double the 

 thickness of the body, they extend four inches singly, or half the 

 length of the animal, thus sweeping the area of a circle eight inches in 

 diameter. 



A thin silken internal coating, perhaps derived from a glutinous 

 exudation of the body, lines the whole tube, while serving as a real cement 

 to unite and strengthen its innumerable parts. 



Notwithstanding the unrivalled expertness, and the expedition of 

 this diminutive architect in advancing its work, it has never been ob- 

 served 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 recom- 

 menced from the foundation. 



Both extremities of the tube are open, which, let it be recollected, 

 is a positive character of the genus, distinctive from all analogies offered 

 by the Sabella, an Amphitrite, or any other architect of its habitation, 

 not undergoing metamorphosis, with which I am acquainted. I cannot 

 speak of the Perthuiria (S/iln-Ua lidtjirn), no entire tube having come 

 into my possession. The length of that of the Tcrebclla is indefinite, 

 but the diameter no greater than allowing the tenant's reversal within 



