Saxicava. MOI.LUSCA. Myad^. 
mantle is also amply provided with muscular fibres, 
running in all directions. The animal thus armed 
attaches itself by the byssus to the rock it wishes to 
perforate, then brings into contact with it this portion 
of its mantle, and setting the muscular fibres into 
motion, soon rasps away the surface. Wherever we 
have a sea -coast of mountain limestone, the substance 
of the rocks is almost invariably found riddled by 
Saxicavce. Sometimes they do considerable damage 
to sea-walls. Some years ago, it was discovered that 
the whole front of the Plymouth breakwater had been 
attacked by them, and great alarm was excited in con- 
sequence for its safety. Luckily these little creatures 
do not bore deeper than six inches, so that unless there 
be a new surface exposed by the destruetion of the 
perforated part, there is not much danger to be appre- 
hended from them. That this action does take place, 
however, is unfortunately too well ascertained ; and no 
doubt exists that the excavations made in limestone 
rocks and indurated clay by the Saxicavse and other 
lithophagous mollusca, contribute materially to alter 
the configuration of the shores. “ Their disintegrating 
influence,” says Dr. Johnston, “ must have been at all 
times, and must continue to be, considerable ; for it is 
not merely by their own excavations that the opposing 
rocks are reduced, but tlirough them water is admitted 
into their interior; and aided by its macerations, its 
varying expansions under various temperatures, the 
ceaseless wearing away of this additional agent while 
it flows or percolates through new channels opened to 
its access, the rock is speedily rubbed down into an 
impalpable dust, or broken up into loose fragments. 
Consider the result: the outline of the shore is altered, 
a barrier to the tide removed, and perhaps some inroad 
is made on the soil.” 
Passing by the PholadomyidcR, we come to the 
Razor- fish. 
Fami LY— SOLEN I D^. 
The Solens or Razor-fish have an elongated shell, 
equivalve, and gaping at both extremities. The liga- 
ment is external, and the teeth are compressed, and 
usually two or three in each valve. The animal has 
a very large and powerful foot, which is club-shaped 
or truncated in front, and not secreting a byssus. The 
species are rather numerous, and are world-wide in 
their distribution, and are usually found living buried 
perpendicularly in the sand, into which they penetrate 
their powerful foot, with its broad finger-like extremity, 
enabling them to sink with great rapidity. They vary 
considerably in shape, and in the structure of the hinge, 
&c., so that it has become necessary to divide them 
into several distinct genera. These are Solen, Ensis, 
Pharus, Cultellus, Siliqua, and Madia. The family 
is represented in Plate 10, fig. 11, by Solen ensis. 
Aristotle was well acquainted with the Razor-fish, 
and has described one species very accurately under 
the name of most probably our common species, 
S. vagina (= marginatus). In more modern times it 
attracted the notice of Reaumur; but ))erhaps what 
gave these animals their greatest celebrity, was their 
excellent qualities as articles of food. They are said 
VoL. II. 103 
369 
to be about the best of shell-fish when properly cooked 
(broiling being the best method), and are eaten in many 
parts of Great Britain, as well as abroad. As has beer, 
said, they generally bury in sand near low wftter mark, 
and the valves of the shell, being connected by epider- 
mis, serve at once as a protection and as a lining to 
their holes. The existing species are distributed all 
over the world without regard to climate. Several are 
common on our own shores, and Professor Forbes has 
given such a graphic account of one of them, the Solen 
vagina, that we extract it entire. It burrows in sand 
near low-water mark at spring tides, to the depth of 
from a foot and a half to two feet. “ They lie in their 
holes nearl}’’ vertical,” he says, “and their places are 
marked by perforations shaped like key-holes, corres- 
ponding to the form of the extremities of their united 
siphons. They are nearly vertical, and do not remain 
quiet, but rise up and down now and then, shifting 
themselves partly above the sand, as if to know what 
is going on in the world above. When the tide goes 
out, they sink deeper. The fishermen then endeavour 
to tempt them out, as little boys would catch birds if 
they could, by putting salt on their tails. The salt 
penetrating the perforation, reaches and irritates the 
extremities of the siphons, and the Solen, annoyed and 
pained, rises suddenly' to clear itself of the nuisance. 
This vigilant human enemy watches the moment, and 
seizes the opportunity, and the Solen — if he can catch 
it ; but unless very quick in his motions, those of the 
Solen may be quicker, and once aware of the danger 
impending, the sensible shell-fish will not rise again, 
but submits patiently to the indignity of being salted 
alive, rather than run the risk of being caught and 
roasted, or else cut up for bait. But if it be not 
touched, a second dose of salt will cause it again to 
rise, which, shows that knowledge and recollection of 
the danger is the impediment to its reappearance in the 
former case. Fishermen in England have a queer but 
absurd fanc}", that when the Razor-fish feels the salt, 
it tliinks the tide is coming in, and therefore rises in its 
hole. If the Solen be taken out of its hole and placed 
upon the sand, it immediately prepares to re-bury itself. 
It stretches out its foot to full length, and then bends it 
so as to use the extremity as a kind cf auger. When 
the end has sunk into the sand, it draws up its shell, 
which, first oblique, and afterwards perpendicular, soon 
becomes immersed and rapidly disappears.” 
Genus Glycimf.kis \=PanoiKea ). — This genus 
has a thick, equivalve, oblong shell,' gaping at each 
end, the beaks nearly central, and with one prominent 
tooth in each valve. Some of the species are very large, 
and are found buried deep in the sand at low water. 
They are found principally in the Northern seas and the 
Mediterranean; but extend also to the Cape of Good 
Hope, Australia, New Zealand, and Patagonia. 
Family— MYAD^. 
The Gapers have a thick, strong, opaque shell, gaping 
posteriorly. Tlie valves arc usually unequal and 
covered with a wrinkled epidermis. The hinge is 
without teeth, and the cartilage, which is internal, is 
placed in a spoon-shaped cavity in one of the valves. 
