TONGUE OF THE LIMPET. 292 
upon the thinnest part of the shell, and is perfectly circular, of a 
champhered form, being wider towards the outward side, and so 
perfectly smooth and regular as to have all the appearance of 
the most beautiful work of an expert artist. It became a 
matter extremely desirable to preserve the mussel, and it seemed 
practicable to extirpate the buccinum. But after we had picked 
up and destroyed many barrels of them, their extirpation was 
at length given up as a hopeless task. The mussels were con- 
sequently abandoned as their prey; and, in the course of the 
third year’s operations, so successful had the ravages of the 
buccinum been that not a single member of the imported 
mussel colony was to be found upon the rock.” Thus the 
engineer, whose skill and perseverance had gained so proud a 
triumph over the waves of the stormy ocean, was defeated by 
an ignoble whelk. 
In the genera which have no proboscis, the tongue, acting as 
a prehensile and rasping or abrading organ, is frequently of con- 
siderable length; thus, in the Ear-shell, it is half as long as the 
body, and in the common Limpet even three times longer than 
the entire animal. From 
the two cartilaginous 
pieces (b b), placed on 
each side of its root, arise 
the short and powerful 
muscles which wield the 
} organ. The surface of 
this curious piece of 
mechanism, a magnified Limpet’s tongue, 
view of which is given 
at B, is armed with minute, though strong, teeth, placed in 
transverse rows, and arranged in three series; each central 
group consists of four spines, while those on the sides con- 
tain but two a-piece. It is only at its anterior extremity (d), 
however, that the tongue, so armed, presents that horny 
hardness needful for the performance of its functions, the 
posterior part being comparatively soft; so that, probably 
in proportion as the anterior part is worn away, the parts 
behind it gradually assume the necessary firmness, and ad- 
vance to supply its place. In the upper part of the cir- 
cumference of the mouth, we find a semicircular horny 
xX 
