OYSTERS AND SCALLOPS. 227 
valve downwards on the bottom of the phial. The 
first thing I observed was the thrusting forth of 
the delicate little foot, an organ which seemed to 
me appropriately named, when I marked its close 
resemblance in form to a human foot and leg, en- 
veloped in a white stocking. What I may call 
the sole of this tiny foot was pressed against the 
side of the glass, feeling about from place to place; 
while with the lens I could distinctly see, im the 
part corresponding to the toe, the opening of the 
fleshy lips, or sides of the grooves, in which the 
threads of byssus are said to be formed. While it 
was thus engaged my surprise was excited by 
seeing it suddenly throw itself with a jerk into an 
upright position; but the action was too startling 
to allow me to see how it was performed. I again 
laid it prone, and though for a moment it closed 
the valves, it presently opened them again, and 
performed a similar feat. This was followed by 
several leaps in different directions, in quick suc- 
cession; but I was still at a loss to know the 
modus operandi. It appeared to me certain, that 
the ordinary supposition, viz. that the action is 
performed by the vigorous opening and shutting of 
the valves, was not the correct one. At length a 
favourable observation gave me a suspicion of the 
truth. I perceived the lips of the mantle (which 
were held in contact, though the valves were con- 
siderably separated) suddenly open to a partial 
extent, as if by a blowing from within. At this 
instant there was a leap in the opposite direction, 
attended with a considerable agitation in the water. 
With. this clue I observed more definitely. Having 
rendered the water a little turbid, in order the 
more distinctly to see any motion of the particles 
