TEREBELLA. 195 
is advancing, either from the impression of the light, perhaps, or from 
the apprehension of danger. 
The sufficiency of the tube for accommodation by no means satisfies 
the tenant, though ample. Like the former, after the temporary repose 
of the morning, its restlessness is displayed through much of the day, 
and augmented as evening approaches. At this period an active search 
for materials commences. Some tentacula secure muddy ladening, others 
are withdrawing grains of sand, and several seize on shelly fragments. 
Much industry is manifested, and meantime the various collections approxi- 
mate merely by contraction of the respective organs retaining them. 
Amidst this, an undulatory action, apparently unconnected with mere 
vital functions, like repeated inflation of the upper part of the body, is 
repeated fifteen or twenty times in a minute, and in an upward diree- 
tion, as towards the orifice of the tube. Next are small masses of ten 
or twelve particles discharged within the orifice, perhaps from the mouth, 
after having undergone some previous preparation there. The under 
lip seems occupied in smoothing that part up and down, or possibly ce- 
menting it with glutinous matter. Undoubtedly the materials are swal- 
lowed. ; 
During several experiments to obtain a variegated tube, I supplied 
the large specimen with a quantity of its red native rock, whereon it 
had been found, now pounded. Next day its body appeared quite red, 
as if from the quality of the contents. Also, its dwelling had been 
augmented. At least two organs or under lips are engaged in preparing 
the materials, for it is improbable that merely in a crude state they can 
be adapted for use. During all this the branchise, however quiescent at 
other times, are in great activity ; yet without discharging any evident 
external functions. 
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 searching after the materials—many in 
collection—many bearing them to the edifice—some quitting their hold— 
others recovering the load—while the architect itself seems occupied in 
