Page:Natural History, Mollusca.djvu/195

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artist. It became a matter extremely desirable to preserve the mussels, 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 thus 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 mussel of a large size was to be found upon the rock, and even the small kind which bred there, are now chiefly confined to the extreme points of the rock, where it would seem their enemy cannot so easily follow them."

The mode in which the Purpura actually performs the operation, has been described by Mr. Spence Bate from observation. "The Whelk," he observes, attacked the Mussel, but it bored where there was no epidermis. I pulled it off, and turned the Mussel upside down (the other valve having more epidermis upon it), but in a short time I returned, and found that the Whelk had turned over the Mussel, and had resumed its operation at its old bore. This I did twice or thrice, with the same result. Giving up the idea of its boring at any other point, I next thought I should like to see how it managed to devour its prey. For this purpose I divided the muscles of the Mussel, so that the valves parted, so as to enable me to observe the work of gormandizing as it proceeded, but to my surprise, the animal gave up all idea of boring, when there was an easier method of obtaining food, and so passed its proboscis between the valves. I think this shows that the Whelk, when it attacks its prey, seeks out for the part most suitable for its operation, and I believe invariably chooses a point