490 MOLLUSCA. 
and the operculated nerite retire into his home, but the enemy, with rasp-like tongue, armed 
with silicious teeth, files a hole through the shell — vain shield where instinct guides the attack ! 
Of the myriads of small shells which the sea heaps up in every sheltered nook, a large proportion 
will be found thus bored by the Avhelks and purples ; in many fossil-shell beds, nearly half the 
bivalves and sea-snails are perforated — the relics of antediluvian banquets. 
This is on the shore, or on the bed of the sea ; far away from land the carinaria and firola 
piirsue the floating acalephe ; and the argonaut, with his relative the spirula, both carnivorous, 
are found in the high seas in almost every quarter of the globe. The most active and rapacious 
of all are the calamaries and cuttles, who vindicate their high position in the naturalist's system 
by preying even on fishes. 
As the shell-fish are great eaters, so in their turn they afford food to many other creatures — 
fulfilling the universal law of eating and being eaten. Civilized man still swallows the oyster, 
and with some the snails are still reckoned a dainty dish ; mussels, cockles, and periwinkles are 
in great esteem with children and the other unsophisticated classes of society; and so are sca]lo23s 
and the haliotis, where they can be obtained. Two kinds of whelk are brought to the British 
markets in great quantities ; the arms of the cuttle-fish are eaten by the Neapolitans, and also 
by the East Indians and Malays. In seasons of scarcity, vast quantities of shell-fish are con- 
sumed by the poor inhabitants of the European coasts. Still more are regularly collected for 
bait; the calamary is much used in the cod-fishery off" Newfoundland; and the limpet, whelk, 
and clam on various coasts. 
Many wild animals feed on shell-fish ; the rat and the raccoon seek for them on the sea-shore 
when pressed by hunger ; the South American otter and the crab-eating opossum constantly 
resort to salt marshes and the sea, and prey on the moUusca ; the great whale lives habitually on 
the small floating pteropods ; sea-fowl search for the littoral species at every ebbing tide ; while, 
in their own element, the marine kinds are perpetually devoured by fishes. The haddock is a 
great conchologist, and some good northern sea-shells have been rescued, unbroken, from the 
stomach of the cod ; while even the strong valves of the cyprina are not proof against the teeth 
of the cat-fish. Many species fall a prey even to animals much their inferiors in sagacity : the 
star-fish SAvallows the small bivalve entire, and dissolves the animal out of its shell ; and the 
bubble-shell, itself predacious, is eaten both by star-fish and sea-anemone. The land-snails afford 
food to many birds, especially to the thrush tribe; and to some insects, for the luminous larva 
of the glow^-worm lives on them, and some of the large predacious beetles occasionally kill slugs. 
The greatest enemies of the Mollusca, however, are those of their own nation ; scarcely one- 
half the shelly tribes graze peacefully on sea-weed, or subsist on the nutrient particles which the 
sea itself brings to their mouths ; the rest browse on living zoophytes, or prey upon the vege- 
table feeders. 
Yet in no class is the instinct of self-preservation stronger, nor the means of defense more ade- 
quate ; their shells seem expressly given to compensate for the slowness of their movement and 
the dimness of their senses. The cuttle-fish escapes from attack by swimming backw' ard and 
beclouding the water with an inky discharge ; and the sea-hare pours out, when irritated, a 
copious purple fluid, formerly held to be poisonous. Others rely on passive resistance, or in 
concealment for their safety. It has been frequently remarked that molluscs resemble the hue 
and appearance of the situation they frequent ; thus, the limpet is commonly overgrown with 
balani and sea-weed, and the ascidian with zoophytes, which form an effectual disguise ; the lima 
and modiola spin together a screen of grotto-work. One ascidian, A. cochligera^ coats itself with 
shell-sand, and the carrier-trochus cements shells and corals to the margin of its habitation, or 
so loads it with pebbles, that it looks like a little heap of stones. 
It must be confessed that the instincts of the shell-fish are of a low order, being almost limited 
to self-preservation, the escape from danger, and the choice of food. Their history offers few 
of those marvels which the entomologist loves to relate. An instance of something like social 
feeling has been observed in a Roman snail, who, after escaping from a garden, returned to it in 
quest of his fellow -prisoner ; but the accomplished naturalist who witnessed the circumstance, 
hesitated to record a thing so unexampled. The limpet, too, if we may trust the observations 
