204 THE ZOOLOGIST. 
methods on the shells, and the readiness with which the Oyster- 
catchers adapt the methods to overcome varying and often un- 
foreseen circumstances. I have thought it best to classify the 
shells according to the places at which they are opened, to 
describe the principal methods and their results in each class, 
and to mention some of the exceptions as they come under 
notice. ; 
I. Mussels opened through the dorsal borders. 
These form approximately seventy-eight per cent. of the 
shells opened by Oystercatchers. Bearing in mind that the 
Mussels in which the dorsal borders are present are the normal 
inhabitants of the banks, that they are available only when a 
sufficiency of moisture permits a separation of the valves, the 
reader will understand that the Oystercatchers must search for 
the gaping shells, and the birds are to be seen at these times 
walking sedately over the banks, their heads directed forwards, 
and their bills in a position ready to strike. Hach Mussel is 
approached in the line of its major axis, and is submitted to a 
careful inspection, usually from the front, though why this should 
be I have not been able to decide. 
If the Mussel meet with approval the Oystercatcher strikes a 
sharp blow with the point of its bill on the summit of the dorsal 
border, apparently to find out whether or not the bill will pass 
between the edges of the valves. Frequently this does not 
happen, and the bird continues the search. When the result of 
the tap is favourable the bill is pushed down into the Mussel 
before the valves have time to close by a number of jerks with 
ereat rapidity and force, until the deepest part of the much 
compressed bill comes to lie lengthwise between the margins of 
the valves. Usually further action is necessary, and it must 
follow soon after the introduction of the bill; but in a few 
instances the bird raises its head, looks about, and then proceeds 
leisurely to clear out the contents. 
When this happens it is probable that the shell has been 
thinner than usual, and the stroke has not been delivered fairly 
between the valves; in consequence a small fragment of one 
valve is driven in before the point of the bill, and through the 
hole thus formed the Oystercatcher is able to extract the con- 
