But if all the remains of the animals were introduced by the hyænas, they certainly in some cases do not occupy the exact position in which they were left by those animals. One of the bone layers (Fig. 91) for instance, actually touched the roof. This, indeed, has been used as an argument in favour of their having been introduced by water, from some unknown repository. But if this hypothesis be admitted, we are landed in the following dilemma: either the introducing current of water must have passed down the vertical passages, or upwards through the horizontal mouth of the cave. In the former case the three bone layers would not have been found in the narrow passages, but would have been swept out into the wide chamber, where the force of the hypothetical current must have abated. In the latter case the great bulk of the remains would have been found in the chamber, and not in the smaller passages. Moreover, the absence of marks of transport by water, and especially of that sorting action which water as a conveying agent always manifests, renders the view of their being so introduced untenable. On the other hand, the horizontality of the layers of bone, and the presence of sand and of red earth, imply that water was an agent in re-arranging the bones and in introducing some of the contents of the cave. The only solution of the difficulty that I can hazard is the occurrence of floods from time to time, during the occupation of the hyænas, similar to those which now take place in the caverns of the neighbourhood. A few years ago, the outlet of the Axe in the great cave was partially blocked up, and the water rose to a height of upwards of sixteen feet, leaving a horizontal deposit of red earth of the same nature as that in the hyæna-den. Now if we suppose that similar floods were caused by an obstruction in the ravine below the hyæna-den, it may have been flooded, just as the upper galleries of the great cave, and the water laden with sediment might have elevated the layers of matted bone, and some of the scattered remains on the surface, while the current was insufficient to disturb the stones, or to affect to any extent the deposits of former floods. The buoyancy of the organic remains is not required to be greater, on this hypothesis, than in that of their having been introduced by a current through the vertical passages. Some of the wet bones taken straight from the cave were sufficiently light to be carried down by the current of the Axe.