NOTES ON THE OYSTERCATCHER. 203 
excavations in the sand or mud, and many have been carried to 
bare patches of rock to be cleared of their contents. 
Careful examination furnishes an important clue to the posi- 
tion the shells occupied during life, and therefrom to the manner 
in which they were opened. It will be seen that of the shells in 
which the valves are still united many have the dorsal borders 
uppermost, and a lesser number the ventral borders; and of the 
shells in which the valves have fallen apart, some have the 
ventral borders adjacent and others the dorsal borders. The 
position of these shells should be compared with that of the un- 
opened Mussels on the banks. The majority rest with the 
dorsal borders uppermost, and are fixed securely to the ground 
by strands which emerge between the ventral borders of the 
valves. In few instances is the converse true. Occasionally 
they lie in a vertical position, the posterior ends being superior. 
In the tightly closed shell the edges of the valves are in perfect 
apposition, with the exception of the middle portion of the 
ventral border. There a long and narrow fissure with rounded 
edges is present. This fissure is the weak point in the Mussel’s 
armour, and it is seldom exposed on the open beds. Shells so 
placed are sought for eagerly by the Oystercatchers, and form 
the exception to the rule that dried and therefore tightly closed 
Mussels are left alone. When Oystercatchers are seen at work 
on dry Mussel-scalps it may be taken for granted that they are 
searching for these Mussels, and I have found repeatedly in 
these cases that only those Mussels were opened of which the 
ventral borders were uppermost. While the Mussels vary in 
size within wide limits, those which are attacked by the Oyster- 
catchers agree closely in dimension with one another. One and 
a quarter inches to one and five-eighths inches in length by half 
an inch to three-quarters of an inch in breadth denote the normal 
variation. I have not seen Mussels of larger size than one and 
five-eighths inches by seven-eighths of an inch opened, and it 
would appear that Mussels smaller than one inch by half an 
inch are taken only when larger sizes are not available. 
We have now to consider the way in which suitable Mussels 
are discovered, the manner in which they are opened, and how 
their contents are removed. Difficulties arise at once by reason 
of the variety of methods in use, the variable effect of these 
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