The change to the circular tumulus is not accompanied with any indications of alteration in the arts of its constructors. Stone weapons and implements are of frequent occurrence in the latter, and particularly in the bowl barrow, though no distinctive evidence has yet been noted in relation to the most common forms of tumuli, sufficiently marked to be resolved into any general rule, save the very natural and obvious one, that the larger ones appear from their contents to be the more important. It is manifest, however, that some art was always exercised in giving to the tumulus an artificial form. Neither the bowl nor the bell shape is that which earth naturally assumes when thrown up into a heap. The form is therefore a matter worthy of further observation, and may yet prove a legitimate basis of stricter classification in reference to the era or race, than that now attempted. The bell-shaped tumuli are not very common in Scotland, but where they do occur they are generally of the larger class, though not always distinguished by any marked peculiarity in their contents. Such was found to be the case on opening the Black Knowe, which appears from a drawing of it to be a bell-shaped tumulus, and is one of the most remarkable for size in the parish of Rendale, Orkney. It was explored in February 1849 by Mr. George Petrie, a zealous Orkney antiquary, in company with Lieutenant Thomas, R.N., while engaged in the Admiralty Survey. I am informed, however, by the latter, that its shape was by no means uniform, and viewed from some points it differed little from the common bowl barrow, of which it is computed that above two thousand are still to be found scattered over the Orkney Islands alone. In the centre and on a level with the natural surface of the soil, there was found a small chamber or cist of undressed stones, measuring eighteen by twelve inches, and containing only an extremely rude cinerary urn, filled with bones and ashes mixed with clay.