Norwich Castle Museum. 127 
habit of burrowing in the sandy shore, but a few which 
prefer a muddy bottom, are found at greater depth. 
These are the SoLentp&; the members of the typical 
genus, So/ex, are known, from their form, as Razor 
Shells, there are several species of very unequal size ;_S. 
stligua is very common on some parts of the coast of 
Norfolk. We must pass on to the family of 
Myip@, known as ‘“‘Gapers,” from the valves not 
closing at the ends. Some of the species are used 
for food, especially AZya arenaria, which is common 
on the Norfolk coast; they all burrow in the sand 
within the littoral zone. Other genera are Panopea 
and Saxicava, in which latter genus we first find a 
tendency to excavate a home in solid rock, Saxzcava 
rugosa inhabits the lowest verge of spring tides, and 
makes its home in limestone, chalk, or even sand- 
stone. The next genus, Venerupis, has the same habit, 
and specimens of V. zrws will be seen embedded in 
the rock. Gastrochena dubia, of which specimens 
from Weymouth will be seen, is said to penetrate 
not only limestone but even granite. 
We now come to the family PHotapip#, the mem- 
bers of which inhabit a thin, white brittle shell, rasp- 
like on the exterior, and open at both ends. They 
excavate holes in rock and sand, maintaining a vertical 
position; here they permanently remain, extruding 
their siphons to secure passing food. Several species 
will be noticed, some zx situ. Teredo is the dreaded 
‘‘worm,’ so destructive to any wooden structure 
@xposed to the action of the sea. The shell is 
globose, and the burrow, which may be a foot, or 
perhaps two feet long, is lined with shell. These 
animals, like the boring /#olas, however thickly 
they may inhabit the same piece of timber, never cross 
the burrows of their own kind, but by some means 
always avoid them. ‘There are four British species, 
