212 THE ZOOLOGIST. 
The position in which the bill is introduced, the quickness 
with which the Oystercatchers remove the anterior and posterior 
parts of the molluses, and the interesting cases in which the bill, 
after it has been sunk vertically between the borders, is borne 
down between the posterior margins, destroying on its way the 
posterior adductor, and is pushed on at once to cut through the 
anterior muscle, go far to prove that the Oystercatchers are 
acquainted with the position and relative importance of the two 
muscles, and fully realize the necessity for their early de- 
struction. 
The fractures, when they occur, depend primarily for their 
production on the relative strength of the shell, the adductor 
muscles, and the ligament; their situation and character are 
determined by the position in which the force is applied, the 
position of the muscles and the ligaments, and the direction of 
the lines of least strength in the shell. 
In these notes I have attempted to describe the ways by 
which Oystercatchers deal with Mussels; I have shown how the 
Oystercatchers are limited to certain Mussels, how entrance to 
the shells is effected, how the valves are separated so as to pre- 
vent their adduction while the molluscs are being devoured; I 
have brought forward observations which seem to prove that the 
Oystercatchers, far from being actuated by blind impulse, on the 
contrary proceed deliberately to remove certain structures which 
hinder the achievement of their desires; and I may say with 
truth that we have in the Oystercatcher a living illustration of 
the principle of the lever, by means of which a comparatively 
feeble instrument is enabled to render the stoutest resistance of 
no avail. 
It remains for me to point out that interest must centre largely 
on the manifold ways in which the bill is employed, and on the 
attempts which may be made to assemble its numerous modes 
of action in the order of their development in Time. 
