If we take a Mussel in our hand we shall find it perfectly impossible to force its valves asunder, without the aid of a strong knife or other instrument; yet the Common Whelk, fleshy and insignificant creature though it be, will consume the animal within, and make the valves fly open in a brief space of time, by means of its soft tongue. But leaving such general remarks, let us suppose we are standing before a boulder covered with these mussels. Numbers of gaping shells may be at intervals perceived still attached to the rock, but with the interior of each valve so empty and smooth, that we could scarce believe they had ever embraced a living occupant. On taking up one of the valves and closely examining it, do you observe nothing peculiar about it now? 'No.' Take up the other then, and submit it to a similar inspection. Well, what do you see now? 'Nothing,' you still reply, 'unless it be a peculiar little hole about the size of a pin's head, which surely is of no importance.' That little hole was of _vital_ importance to the poor mollusc, for through that aperture the life and substance of the Mytilus was drawn by the voracious Purpura. But the poor Mussel is exposed to the attacks of other enemies--aquatic birds, as sea-gulls and ducks, eagles, vultures. Even water-rats and monkeys may also be included in the list. It is amusing to see a gull, by no means a foolish bird, standing patiently before a Limpet, for example. The animal, unsuspicious of the presence of an enemy, raises his canopy with the view of relaxing his overstrained muscles, and is instantly toppled over by the intruding beak of the bird. If unsuccessful in his first attempt, the gull is well aware it would be useless to try a second time at that tide. But if a Mussel be the object of attack, it is wrenched from its seat, raised to a certain height, and then allowed to drop upon a stone with the view of breaking the shell. In one locality called Mussel Bay, Mr. Barrow says he disturbed some thousands of birds, and found so many thousands of shell-fish scattered over the surface of a heap of shells, that, for aught he knew, would have filled as many thousand waggons. This habit of the feathered tribe was, by the way, well known to the ancients, and I may be pardoned relieving my pages by a quotation on the subject from the 'Shepherd's Calender' of Spenser, whose exquisite descriptions of natural history are as marvellous as his allegorical poem. The author of the 'Fairy Queen' thus humorously reads a lesson to an ambitious man,--