could be introduced without the _Nassa_ smelling it, and coming up to see what they could get.[301] Any one can experiment for themselves on the olfactory powers of our common snails or slugs. Moquin-Tandon records[302] two interesting cases, one communicated to him by letter, the other occurring to himself. His correspondent, a M. Parenteau, was one day walking along a dusty high-road, when he noticed, near the middle of the road, an empty bean-pod and two Arions eating it. Attributing the meeting of feeders and food to mere chance, he was walking on, when he noticed a second bean-pod, and, about two yards away from it, a third _Arion_, hurrying straight towards it. When the _Arion_ had yet more than a yard to traverse, M. Parenteau picked up the bean and put it in his pocket. The _Arion_ stopped, raised its head, and turned in every direction, waving its tentacles, but without advancing. M. Parenteau then carried the bean to the other side of the road, and put it in a small hole behind a piece of stone. The _Arion_, after a moment’s indecision, started off straight for the bean. Again the position of the precious morsel was changed, and again the _Arion_ made for it, this time without being further tantalised. M. Moquin-Tandon noticed, one rainy day in the botanical gardens at Toulouse, two _Limax maximus_ approaching a rotten apple from different directions. He changed the position of the apple several times, placing it at a sufficient distance, to be sure they could not see it, but they always hit it off correctly, after raising their heads and moving their long tentacles in every direction. It then occurred to him to hold the apple in the air, some centimetres above the head of the _Limax_. They perceived where it was, raised their heads and lengthened their necks, endeavouring to find some solid body on which to climb to their food. Several of the land Mollusca have the power of exhaling a disagreeable smell, _Hyalinia alliaria_ smelling strongly of garlic, and _Stenogyra decollata_ of laudanum; but this need not be any argument for the sense of smell in the creatures themselves.