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 while 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 asa 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 Pectinaria (Sabella belgica), no entire tube having come 
into my possession. The length of that of the Teredella is indefinite, 
but the diameter no greater than allowing the tenant’s reversal within 
