FOURTH SERIES.—No. IX. JANUARY, 1872. AN ACCOUNT OF THE OPENING OF A TUMULUS KNOWN AS "TWYN Y BEDDAU,"1 NEAE HAY. This tumulus is situate on a plateau of the Black Mountains, about three miles south from Hay, and at an elevation of 1,200 feet above sea-level. The tumulus was opened during the month of May last. Two cuttings were made, viz. one main cut in an easterly and westerly direction, and a second cut north¬ wards from the centre. The depth of the cutting below the surface of the tumulus was 14 feet. The accompa¬ nying ground-plan and section will enable the reader to better understand the descriptions hereafter given. In commencing the main cut, at about 6 inches from the surface was found stone pitching, but very irregular, the stones being similar to those found in the soil of the district. At a further depth of 4 ft. 6 ins. a second pitching or pavement, more compact than the first upper layer, occurred. Immediately above this second pitching was a layer of charcoal. The remains of charred wood were considerable, and intermixed with the soil for at least 12 ins. above the pitching. Below the second pitching the nature of the ground was very different. It was quite soft, and admitted easily a stick for some distance : in fact, it was full of 1 "Twyn-y-Beddau"on the Ordnance ; the meaning being, "Twyn" for tumulus, and " Beddau," graves (the tumulus of the graves). 4'TH .-5ER. VOL. III. 1