At places where dead Snail-shells are few and far between, as in the crevices of rustic walls, each Bee occupies by herself the shells which she has found. But here, in the quarries, our crop will certainly be a double or even a treble one, for both Resin-bees frequent the same heaps. Let us, therefore, lift the stones and dig into the mound until the excessive dampness of the subsoil tells us that it is useless to look lower down. Sometimes at the moment of removing the first layer, sometimes at a depth of eighteen inches, we shall find the Osmia's Snail-shell and, much more rarely, the Resin-bee's. Above all, patience! The job is none of the most fruitful; nor is it exactly an agreeable one. By dint of turning over uncommonly jagged stones, our fingertips get hurt, lose their skin and become as smooth as though we had held them on a grindstone. After a whole afternoon of this work, our back will be aching, our fingers will be itching and smarting and we shall possess a dozen Osmia-nests and perhaps two or three Resin-bees' nests. Let us be content with that. The Osmia's shells can be recognized at once, as being closed at the orifice with a clay cover. The Anthidium's call for a special examination, without which we should run a great risk of filling our pockets with cumbersome rubbish. We find a dead Snail-shell among the stones. Is it inhabited by the Resin-bee or not? The outside tells us nothing. The Anthidium's work comes at the bottom of the spiral, a long way from the mouth; and, though this is wide open, the eye cannot travel far enough along the winding stair. I hold up the doubtful shell to the light. If it is completely transparent, I know that it is empty and I put it back to serve for future nests. If the second whorl is opaque, the spiral contains something. What does it contain? Earth washed in by the rain? Remnants of the putrefied Snail? That remains to be seen. With a little pocket-trowel, the inquisitorial implement which always accompanies me, I make a wide window in the middle of the final whorl. If I see a gleaming resin floor, with incrustations of gravel, the thing is settled: I possess an Anthidium's nest. But, oh the number of failures that go to one success! The number of windows vainly opened in shells whose bottom is stuffed with clay or with noisome corpses! Thus picking shells among the overturned stone-heaps, inspecting them in the sun, breaking into them with the trowel and nearly always rejecting them, I manage, after repeated attempts, to obtain my materials for this chapter.