40 
the bathing ponds. A suggestion has been made to plant the small 
mussels on the north bank of the river, where gravel and stones 
abound, and where there is a large stretch of land left uncovered by 
the tide every day, but they would hardly get enough food there for 
them to grow to any size. A better plan would seem to be for the 
fishermen to plant more mussels up the river, as they have already 
done in a small way with success. There appears to be no reason 
why, with more cultivation, this bed should not yield enough bait 
for the fishermen both of Berwick and the Spittal. 
ENEMIES OF THE MUSSELS. 
The mussels on this coast have not many enemies, but by far 
the most important of these is the starfish, Asterias rubens, which 
constantly preys upon them. A formerly flourishing bed near the 
Tyne has lately been exterminated by this starfish (see ante p. 29), 
and it is a bad enemy nearly everywhere. Purpura lapillus devours 
the mussels on the scaup, Holy Island, and here in parts the 
devastation caused by this small and very destructive mollusk is 
great. It does not, however, appear to be a scourge elsewhere. 
The only possible way of dealing with such foes would be to destroy 
all starfish whenever found, and to collect the Purpura lapillus 
systematically, and also its spawn, and destroy both. It would 
probably take a very long time to make any perceptible difference 
in the number of Purpura lapillus, as they are so abundant, but if 
the vase-sliaped spawn, so easily seen, were destroyed whenever met 
with, the numbers are bound to diminish in time. 
Many birds eat the mussels, notably the Oyster Catcher and 
species of wild duck,* especially in the Winter. The Oyster 
Catchers on this coast often have their stomachs full of the remains 
of mussels, with cockles, limpets, and chitons, but the prevailing 
opinion among the fishermen is that they eat more limpets than 
mussels, and perhaps these birds are not common enough to make 
any material difference in the number of mussels. 
In the Budle and Holy Island mussels, especially the former, 
the shells are much attacked by the boring annelid Polydora ciliata, 
which also frequently invades the periwinkles of the Holy Island 
scaup. Inside the mussels several larval Trematodes were found. 
* For a list of birds that eat mussels see “ Some Trematodes in Mytilus,” by the writer. 
Proc. Univ. Durham Phil. Soc., 1906, p. 231. 
